Looking to buy/build 500-600 fwhp 360

Trans is a fresh rebuild, and it is the "Hemi" 4 speed. My dad had it build for drag racing. He has the synchronizers modified, something about every other tooth removed. I think the 3rd member on the 8 3/4 is a posi that has been rebuilt. I figured the trans would hold up if they were behind Hemi's. I guess if it breaks I will have to upgrade to a Lenco and Dana 60. Just kidding, don't really want to do that...
your transmission has been "slick shifted"! google herb mccandles slick shifted! you can launch it and turn to red line, and just grab your next gear with out depressing the clutch! being a hemi 4 speed means its got stronger shafts in it! had one herb fixed in a 71 duster, 2nd biggest mistake i ever made was letting that car go! more fun than a lot lizard with a quarter slot behind her ear!!!