Hello Ken, welcome to RCU.
If it helps I am just finishing mine off, using like Bokis a Saito 170R. I found with that I am having to bolt about 2 1/2 lbs of lead to the bulkhead as well as a 4300 mah 5 cell Nimh battery.
You should have a better time using a heavier engine.
Sounds like you fly similar to myself, there is an art in flying warbirds to look scale, especially landing![X(]
You will find people on this forum very helpful, if you get stuck just put a post on.
In your kit can you tell me if the four aluminium joining brackets for the wing halves are identical in size?
Gary.