I'm gonna pass along some advice I've learned while building my roadster, which isn't finished yet.
There are alot of different variables involved when building cars from scratch. Your best friend is the "mockup". That's the only way you can be sure the parts you have chosen will work together. My experience with the "kit" type t-buckets is that either the chassis' are too short (Total Performance,CCR) or too long (Spirit Ind.) even with a chevy V8. Don't try and modify there ugly designs to fit your engine.
Start from scratch, and figure out what works. Be sure to have the wheels and tires you intend to use. I think you should begin your mockup with a Model A wheelbase of 103.5". That is with a spring over axle frontend, with the axle underneath the frame. That is how mine is setup. I'm using a stock Model A chassis with a 6 inch rear kickup, tranverse spring over rear axle. Front is stock crossmember, reverse eye spring and 4 inch drop axle. It's forties style, so it's probably a little too high for you and it's not gonna give you enough engine room.
So, you need more engine room and you want it lower. Start with the front suspension. You need to get that axle out from under the frame. The axle hitting the frame is the limiting factor. Go suicide, but keep the spring on top if using a deep drop axle. For a shallow drop you can put the spring behind. You can't forget basic suspension priciples. A deep drop and spring behind coupled with a suicide mount is gonna give you scrub line problems. Keep the steering in mind also. A lot of those kits have the tie rod in front of the axle. That's no good, the Ackerman is all fouled up.
Ditching the Model A crossmember (theoretically)in favor of a suicide mount will increase the wheelbase, but not the overall length of the frame. It will give you more engine room and get you lower. If you look at a Total Performance type car you'll see that they are suicide front suspension but they kept the shorter wheelbase. The proportions are all wrong. The Spirit type chassis' have the same suspension but they also extended the frame. Even with a longer six cylinder motor, there is too much of a gap between the radiator and the front end. The wheels are just floating in space. Also use a falcon/mustang radiator, it will provide enough cooling and is thinner than the street rod type radiators, plus it's 1/4 the cost.
Now back to the rear. With a 26-27 roadster body you can't change the axle centerline from the stock position. These bodies have wheelwells, if you move the axle centerline, it will look funny. You want it low but you need to factor in the trunk. Increasing the kickup will get you lower, but it will eat up all the trunk space. On my chassis I have a stock spring on top Model A spring and crossmember with a 6 inch kickup. I takes up a lot of trunk space, and isn't all that low (the body is also channelled 4 inches by the way). If I want it lower I have the option of lowering the spring (reverse eyes, dearching) or I can move the spring behind the axle and down. This would necessitate extending the chassis but not the wheelbase. Doing so would lower the car and increase trunk space. For coil over shocks, these priciples apply with a little alteration.
I mentioned my body is channelled. In case you don't know, it's the lowering of the body over the frame rails. This lowers the overall profile of the car but takes up valuable interior space in the process. It's not a problem in my situation because I'm short and skinny and I'm planning on running a low profile seat. If you're tall and like a cushy seat, then you have a few options, which can be combined in different ways. You can choose to not channel the body. You can kickup the frame rails in front of the firewall and behind the seat to get the car lower but save the interior space. Or you can build a perimeter frame so you drop the seat down between the frame rails. Or a combination of all four. Also factor in your transmision choice.
The main thing here is to build a car that fits you and doesn't involve costly bad design decisions. You want to avoid buying parts that you can't use, because either they don't fit or require drastic changes to other parts of the buildup. And you want to be able to drive the thing when your're done. It's no fun to spend lots of effort and money on car that you can't drive.
If anyone has more questions I'll be happy to help.
And one more thing, a fun, powerful T should cost less than $5K. If you spend more than that, you've spent too much.