I learned way too much today.
@p1001 - FYI since I know you will be doing something similar.
So again, I pulled the side rails of from the sides and top, cleaned them up, and repainted them. Then got drips, and sanded and repainted them AGAIN.
Then I had this GENIUS idea! I'd put the top rail on the old playfield, clamp it in place, and drill the screw holes. I got a template and checked and the screw holes looked right.
NOPE. They were off by around 1/4 inch.
So I thought I'd pre-drill the holes. I'm drilling from the bottom up, so I figured I'd skip the recommended bit. Yeah, not a good idea. Fortunately, any damage is hidden under the rails, but it's time to buy a bit set. I did drill the holes in the playfield, and then after mounting and getting the top wood in place (because everything keys off of that except the inside ball lane rail) and screwed it into place.
I had to change - I had 2" c-clamps to keep the game on the rotisserie, but the side wood rails wouldn't fit through them, so I grabbed some 4" c-clamps and my wood clamps from my shop, and used those - and it works great.
Once the top wood was in, it was easy to install the two side rails. You don't need to pre-drill the side rails if you use the same ones - they are soft wood. Even underdrilling made them a bit of a weak connection. I'll probably get 1/4" longer screws in the end.
I also got all the flange nuts transferred over. The 6 for the top ball arch - the holes were undersized, so I drilled those out one size under, and then pounded those into place with a dead blow hammer.
Also, for my larger clamps, I used a piece of tire patch material under the metal to protect the playfield.
Now for the painful part - do I take down the game and transfer a known wiring harness, or use the one on the donor playfield which has a number of parts missing, and then just harvest the rest for spare parts down the road?
Pictures or it didn't happen.
First picture - where I ended today.

Second picture - using the larger clamps and tire patch material, while holding the side rail in place with the wood clamps
Last picture - threaded inserts installed and top wood perimeter rail.
