mechanical or vacuum distributor?

[IndyCuda]

I am rebuilding a 340 that will be in the 375-400 HP range. I am upgrading the ignition to with a msd coil pack, 6A box and distributor. Should I be looking at mechanical or vacuum distributors or a combo?

[ShelbyDogg]

Combo if you want it to idle smooth. Hook your vacuum pod to manifold vacuum. It advances the timing at idle to smooth it out and keep the engine cool.

[IndyCuda]

Will do, thanks!