I would just use a performer RPM, they are just over $200 if you shop around and the best compromise between all the designs and work well everywhere.
A 68 charger with a low deck- M1 / 4500 dominator combo. M1 / 4150 - 950 Holley PERF RPM / holley carb combo. All fit with a small drop bas air cleaner.
So far my favorite on my engine, 10.4/1 470 is the eddy rpm with a 1000cfm annular booster holley.