you could piece together and 03 longblock for fairly cheap. probably 5-6k.
instead of spending the 500 or so getting a heaton for it, i would just go straight to a KB/Whipple though and do injectors, bap, maf, ect all at once.
if your not going to take advantage of the 03 shortblock strength, then id just built a boosted 331/347 instead. easier and in the end same or less money for the power.