Weeds, I tried to email a reply to your PM but it bounced. Click the link to my "Trucks" website then click on "54GMC" then "Front suspension" to see the problems I ran into with the kit from CPP and how I solved them.
As far as clearance with the tranny, I didn't have any problems. I'm using a TH200-4R behind a 248.

"It's just a phase. He'll grow out of it." Mama, 1964

1956 Chevy 1/2-ton 3100
1953 Chevy 6100 "The Yard dog"
1954 GMC Suburban Now with a new proud owner.