What I did was to get a Doug Nash Corvette 4+3.
Nobody likes this thing but me.
It is a aluminum case 4 speed with an overdrive glued on the back.
Working examples go for about $600-$1000.
You can get the 4 speed part for about $150, but the overdrive is what makes it fun.
In essence, it gives you 7 forward speeds. You can run 4:11's and fry the tires, and go through the gears and
With the flip of a switch, you have overdrive.
The 4 speed portion is rated at 475 foot pounds of torque. So blast away! You just use the 4 speed as fifth, after you stop abusing the trans. The overdrive is only rated at 300 ft lbs. So by the time you have wound it out in 4 gears, the overdrive will take what's left.
Here's what it looks like bolted to my engine.....and yes, that's an 89 corvette engine with a carb.
You have to make your own rear mount and shifter brackets. The fourspeed is an aluminum Saginaw clone as done by Doug Nash
kind of like a gear splitter.