Go with AFRs or trick flow heads, they are way better than any ford racing head...IMO I would go with a KB if your going to keep it under 10# of boost.
We have been in the 11's with our stock longblock blower car how fast you want to go ?
Damn...for 12k you should be looking at building a serious motor before even looking at a blower. i would start with a big inch dart block stroker....maybe a 392? Toss some AFR 205's on there with a TFS-R or EFI Victor intake and a custom cam. Maybe a solid roller?? That should run you a pretty penny...but i think you will still have enough cash left over for a sick C4 with a custom stall and manual VB...all for under 12k. All motor that would put you in the 10's. Probably around 450rwhp.