You need to place the engine as far back as you can. Rob the Viking ( a guy from Britain, posted a picture of his 1969 250 six, and was putting it into his Capri II (1978 to 1983) has dissapeared from this forum, but he was doing a similar thing.
There are space issues becasue of were the heater/through flow ventilation box sit. Most guys putting 350 Chev V8's hammer the box inwards, and run the V8 very close to the rear of the engine bay. On a six, the centre of balance of the engine is further forward, and the best option is to set it back as far as you can. If you use the existing postion for the C4, it will put the engine further forward. Bearing in mind the 73 to 74 GXL 3000 got a standard American C4, and the transmisison and T-bar are all factory items, you should consider leaving the transmission where it is, and decide to lower the 250 engine down 1.5 inches lower than the V8 would have sat. Talk to the 66Mustang, and see if he will sell you some low mount 250 engine mounts.
The best sump to use is to cut and shut the later Fox car 200 or 5.0 pan to the existing sump. All 250's were front mount sumps, with the possible expecption of the 72 to 76 Torino 250's. There will be a good deal of welding. If its a 250, you may have to place an external oil pan mounted dip stick, rather than redrill the back part of the block to place a rear mount dip stick.
The rack and pinion steering and cross memeber are okay, but its a good policy to have it reconditioned.
Must guys in Australia and New Zealand add a heavy duty cross member, and use Austin Princess or Ambassador twin pot calipers on the existing brakes. Volvo 264 front discs are also but the stud pattern on the Ovlov is smaller than the 5-stud Ford pattern.
There is heaps of room for the engine, but the earlier Capri II bonnet bulge might be a good idea to clear the rocker cover and carb, as the 250 is over 20 inches from the centreline of the crank to the top of the carb.
