I just saw this thread. I'm swapping a stock XR2 engine into a car I'm building and I have to do something with the axles.
I'm using 1995 Thunderbird axle shafts (they have an O.D. of 1.08" and I believe they are 36 splines). The XR 2 inner CV joints are 1.08" O.D.. I measured the cut part of the spline to be 1.01" - 1.02" or so.
Dutchman axles (
http://www.dutchmanaxles.com/services ) told me they can respline my T-Bird axles to match the XR 2 inners for $135 for the pair.
If the O.D. of the V6's axle shafts is equal to or larger than the XR 2's inners (1.08") resplining may be an option for you.
If not, "The Driveshaft Shop" ( 704- 633- 2380 ) can make you new axle shafts. They quoted me $600 - $800 for the pair. That's certainly not cheap but it's not a deal breaker either. I can't remember for sure but I think they told me they guarantee the new shafts are good for 600 hp (don't quote me - it's been a while since I talked to them).
Splicing axles is not out of the question either. A decent machinist with a good lathe can turn the larger shaft down to the same diameter as the smaller shaft (if necessary) then chamfer the ends. A good welder can weld them, slip a piece of DOM over the weld and weld that. Drill a couple hardened steel pins through each end and I really think they'd hold 300 horse without too much trouble.
So the axle part of this problem isn't insurmountable.
Additionally, switching to a hydraulic slave cylinder at the trans isn't hard at all. Wilwood makes a really nice "pull-type" slave cylinder that you can fit without too much trouble.
(I'll replace that 5/16" bolt with a grade 8 bolt)
Make a bracket with some good bracing and it should work fine:
So there ares some possibilities for the axle shafts for you and the clutch / slave cylinder mods are easy and will cost you around $100.
Hopefully that'll help y'all a bit.
Good luck!
Dave