Yes there is the debate between batch fire and sequential. It really depends on how radical the motor is IMO. If you're developing enough vacuum to run power brakes, I don't think you're going to notice much difference between the two compared to a 700 or 800hp race motor. Also depends on your budget, while no efi system is for the faint of wallet, the MS is the cheapest.

Currently MS only does batch firing, however the MS-II Sequencer is in beta testing right now. MS-II Sequencer does sequential plus individual cylinder fuel trimming.

For port efi versus tbi, that's a tough one. The stumbling block is the price of a decent flowing TBI. The GM 454 units don't even flow well at all in terms of air or fuel and to get the flow up there costs some $$$. If you're making 250-300hp, you're probably okay, but that's about tops. I have the cfm for them (converted from 2bbl flow to 4bbl flow) as well as the flow size of their injectors on my computer somewhere. I just remember the GM tbi's just aren't that good in stock form. And used 454 tbi's aren't the cheapest things out there either for the used piece you're getting. They can be modded for more flow but you quickly dig yourself into a hole in which you could have gone port efi for near the same price.