A 904 would definitely help, but since you just bought a converter, I think the $$ for a new converter and getting the driveshaft shortened could be better spent. I wanted a 904 for my truck, but am keeping the 727.
I highly recommend a RMVB. Although, they are pricey now. Once you drive one, you'll want one in everything you drive.
I think the 727 rebuild makes since, but doubt you'll pick up 2.8 tenths from that alone. I do think Drag Truck has a 7.99 in it though.
I also suggest building it yourself. And if you need any help, jpar offered, and so do I.
