i have the gm 847 not installed yet, im looking to buy a set from somewhere, looking for the biggest nastiest heads that will work well with my std. bore LT1 with the 847. car is not daily driven. car is a 6 speed, with a re ringed/new bearings motor out of a 93 or 94 vette so it has 4 bolt mains. price isnt realy an issue but i dont wanna buy a set of heads thats worth more than the car ill be buying them at the end of this month. sorry if im vauge, if i missed something i can probably answer it.

 

The most economic approch is to locate a good set of LT1 casts and have them ported by LE or AI, they will also fit larger valves and valve springs.
It'll be great if you can get a bare set of LT4 heads and have them ported and assembled by LE or AI.
Another more costly option is to do the same with a bare set of AFR heads. The advantage of the AFR is the deck thickness that better suits FI applications.
Trickflow are the new kid on the block, they are good for FI and stroker application due to the large chamber volume, but n your case your CR will drop and hurt power.