4-5G...well you had better start with a full rebuild..rings barings, seals etc..and i would prolly suggest a hybrid..smallport bottom end + bigport head..advantages of this is..bigger/stronger crank and general internals, and the added novelty of oil squirters..then yeh.. deck the head a little, quad throttle bodies, on a street motor i wouldn't go over board with the cams cos it would suck driving to work and in traffic etc..Aftermarket ECU, a set of those famous extractors from Anthony. 2" mandrel zorst, i think you shoudl get away Just with 5g's..you will have a very tough motor though!
ohh..what do you class as Decent power? cos as a diff thread stated an NA motor you kinda need to improve on a range of things and they will work well together..depending on cams..i don't see this setup getting anywhere under 160hp (motor hp)