Leaf to Coil swap veterans...I need your experience

[68GMCCustom]

I am swapping a '72 SWB C10's front and rear suspension, steering, crossmembers, and brakes on my '68 SWB GMC frame. The frame are definitely different, as the leaf frame has small reliefs in the frame to reinforce it on each side of the leaf spring hangers. I left the rivets in the holes and ground it smooth before painting, so from the outside it looks like nothing was there.
I've also noticed that the coil spring frame has some reinforcing plates at the crossmember the shocks mount to. I plan on cutting these out to use on the GMC frame. I also plan to box the frame in front of and behind the trailing arm crossmember.

I have noticed several differences in the leaf frame vs coil frame. The leaf frame is also an early one being a '68 and the coil frame is a late model being a '72. Does anyone thats done one or more of these swaps...have any special information to help me have a successful swap? I worry about everything being strong enough for my 500+hp motor.