I think there are two sets of bolt holes in the frame for the trans cross member, I'm pretty sure I saw them while crawling around under my '73. Just check before you start cutting stuff, you may be able to just move it back to the next set.
I crawled under mine the other day and noticed the trans xmember isnt actually bolted to te bottom of the actual frame rail. There a hole on the xmember itself and one on the frame a couple inches back. I still have alot left to fix on this thing from what the PO did
I guess I would have to see a picture of it, I thought they were bolted on the frame, it's been a while since I've seen my truck...
Im pretty sure I used the W55 slave, but I might have reused the L43 slave. If it bolts up to it I reused it, but I think I had to modify the rod that pushes the throw out arm, either shortened or lengthened it. And throw out bearing has to be for the W55 as they are a different size. Everything else was left alone.
If you're still looking to do this its possible. I swapped a W58 from an early Supra I beliave the celica bell housing bolts right up to the tranny. I bought the original slave for my 4 speed and shave the pin down a bit and it worked perfectly. Cut the middle of the crossmember out and moved it back a few inches to bolt the trans mount up. My old drive shaft was just about the perfect length (Long Bed) but I had to get it modified because the tranny Slip-Yoke was different. My gas milage inmproved dramatically and the length of the gears were great. I was even able to use my 20R clutch!
so you said you had to change the slip yoke to get your w58 to work. the reason i ask is i recently peeked under my truck and im concerned im gonna have to change out my driveline cause mine is bolted to the output of my l43 trans and my w50 trans has a slip yoke. is there any recommendations on this swap.