Jammer, I recently helped a friend with his 1989 GL1500 trike conversion. We found parts/pieces for a California SideCar trike and bought them cheap. They included: 1 complete rear-end housing with cracked housing, a couple of CSC bodies for the GL1500's for a very, very good price. I didn't see or hear what body type your gonna use ..if any??
He bought a bike and we finished it earlier this year.
We used the stock swing-arm...with added bracing (we got cracks in it after only a 100 miles) 1/8" steel plate to stressed areas and other areas...just because. We also welded our single tube to the swing arm which then mounts to the "stock" studs on the mounting plates on the front of the axle tubes. This is much like a "stock" CSC arrangement. This unit also uses 3 shock units...2 stock Honda shocks and 1 stock Honda air shock. We mounted all these stock in near stock positions/angles on a 1" tubing (.125" wall thickness) welded to top of tube that connects to rear house axle tubes. Mounting tab/s location for the bottom position is important for good ride and ride height.
Your sub-frame tubing is a bit "overkill" as 1" tubing with .125" wall thickness is good & strong enough.
The CSC rear-end is a Mustang II with 3.00 ratio. But when we built my GL1200...we used a Ford Ranger truck rear (7.5 and changed gears to 3.00 from the stock 3.65) The rear we bought (with the bodies) had a welding flaw on the rear of the "pumpkin", so it was replaced and set outside in the weather...we replaced everything and re-welded the crack. Runs good...no leaks.
We re-drilled axle flanges to run Chevy 5-bolt for better selection of "mag wheels" and wheel off-set.
Mmm, there's other stuff...I got pics somewhere in "puter" if I can figger out how to send to ya of our build.
I got lots of popcorn, so I be watching!!
Just saw your pic of the BIG body...Roadsmith????? Must weigh 125lbs!!!