Recommend me a 5 speed race gearbox

[Jafa]

Down in little old New Zealand, we had a class back in the 80's called Sports Sedans. It was pretty much "run what you brung", with very limited rules - no more than 366 cubic inches, rear wing no higher than the roof or wider than the widest part of the car etc. Back-halved, tubbed, flares, wings, spoilers, engine moved back, or engine in the back, you name it, basically you were only limited by your ability to dream it up.

Anyway, the class was banned overnight sometime around 1990 and that was that, and the cars all got put in garages under dust sheets. Fast forward to 2012 I think it was, and now there is a class called Historic Sports Sedans, and the cars must be as they ran all those years ago. My brother purchased a car and has set about mechanically rebuilding it because it was totally rooted. It's a MK 2 Ford Escort from 1976, running a 350 Chev right back in the engine bay, and currently has a Tremec TKO600 gearbox. This might be rooted too, and also might not be able to cope with the new engine he's getting built.

So, looking for a new ( not second hand ) 5 speed ( 4th gear being 1:1 ) internally shifted ( no external shift rods ), H pattern ( not sequential ) gearbox to cope with about 670?hp and 600ft/lbs minimum. We'd probably prefer synchromesh, but if the killer gearbox is dog engagement then so be it. Budget is not unlimited, but we'll spring for something that'll last the distance.

Everyone loves a picture, so here is the carat the last race meeting:

IMG_8886 by JAFA851, on Flickr