Hey 64Galaxie,
You didn't say what year your 170 is. If your a '64 or later you can use the 68 - 73 dual advance dizzy or the DS2. Earlier 170's have a smaller dizzy drive so the switch to the later dizzy is complicated by a requirement to overbore the drive hole. This is important because the 2V carbs. we typically use (5200, 2100, 2300, DG series Weber) are not set up to support the dual vac dizzy used on the 1960 - 1967 cars, i.e., you have to change the distributors when you go 2V.
Don't know how far along you are with your rebuild, but if not too late I would recommend a 69 - 73 200 head with the 1.75" carb bore. These heads will flow much better than the stock 170 and yet the combustion chamber is very nearly the same size as the 170. Have the 1.75" intake valves installed when the valve jobs is done (3 angle). This process is simple, won't cost any more that a typical valve job, and will improve performance significantly. However, if you do this you will be committed to a carb and dizzy change so check that dizzy drive issue first. If you can't change the dizzy go with the pre 69 200 head and follow the same process. This will allow you to retain the 1.5" carb bore so that you can stay with the dual vac dizzy carb.
If you go 2V, for my money the Holley 5200 is the way to go. They flow almost twice the volume of the 1V's at WOT and run on 1V until you put your foot in it. The benefit is good bottom end torque with top end flow. They are easy to install, tune and maintain. Parts support is very good. Thay are inexpensive.
Distributor. I use, and recommend, the dual advance 68 - 73 dizzy with Pertronix II electroic ignition and Flamethrower 2 coil. Additionally, I have buypassed (capped off) the vacuum advance. As there have been several sessions here on this subject I recommend looking through my related postings for lots of opinion. Also take a look here
www.bob2000.com/dist.htm
While each of these changes will add power you can feel in the seat of you pants (carb & dizzy go togather), if you add a header (6x1), 2" exhaust pipe and a free flow muffler you will increase rear wheel HP buy approx 40%.
Enjoy the process - Steve