"Still deciding on the engine---any suggestions?"
Well, I'd just recommend what I have in my car---same as most everyone else is going to do. It's hard to beat some of those Subaru engines---even the simpler ones provide more power than a sane person is ever going to need plus heat and air if you want them. David Stroud seems to have found the formula for installing a suby---his works better than some makers who install them pretty much exclusively.
I'm not at all hung up on authenticity to the point of insisting on air cooled. I do have a great 2150 cc Type IV engine that floats my boat, that Jake Raby built for me. I replaced the 1915 Type I started with it as I wanted total reliability as #1. Sometimes I feel like the last guy who got shot in WWII as I'm sure I got one of the very last Type IVs produced. That was done January 2010, almost six years ago when Suby conversions were pretty rare. My engine suits me fine and has been bulletproof. It was more expensive than some Suby's too but it has some unobtanium guts and treatments like cryo enhancement and dynamic .02 oz./in race balancing. Made for my driving style of fast cross country touring.
Also there are some fine Type 1's out there that are great.---Danny Pip's Raby built Type I powered Spyder is the quickest replica I have even been in and I'd consider a really well- built Type I spec'd like the ones in many IM Speedsters made by C.B. Performance.. Al Shapiro's Ruby has one and it is super fine and runs all day at 75-80 trouble-free.
If I had it to do over I'd have a Raby built Suby, but I don't have it to do over, and I am so happy with my present set up that I'll stay with it. Some SOCers are having engine swaps done over the winter, switching Type 1s for Subys.
What are you most lusting for, engine-wise, at this point?