[Brian]

I have spent years of my life building up various renditions of 21 stud engines for my 35. I have learnt a lot; what works...culminating with an engine that eats 350 Chevs on the dirt track [FORD- Fantastic On Rough Dirt]. 17 second 1/4 mile in fully street legal 35 sedan. The one advantage of the small 221 displacement engines is, on account of their smaller/ lighter rotating/reciprocating internals, they have a propensity to rev. Therefore, build them to take advantage of this feature. This means, lightening things, letting them breathe, raising compression, and balancing the whole works.
Now once you've done that, it'll no doubt be even slower off the line, which seems to be not what you're seeking. In which case, follow Pete and Tinkers advice. More displacement will get you off the line quicker, but a little, hi revving 221 will go faster.
I admire anyone who perseveres with a 21 stud. Good luck