Terry - I had three of these and I believe I still have a new one left.
Regarding "HEMI", as far as I know, all the SAITOs have hemi heads.
This particular SAITO was my first 4S engine and it was a very user-friendly and smooth powerplant.
I had it on my Euclid which is a very slightly enlarged Sig Chipmunk.
Throttle wired wide open, no modifications (it would probably have benefitted a bit from Bob Reeves excellent intake modification)
Total weight was around 50 ounces and it would do the entire pattern with no problems.
I did win a few firsts in intermediate and advanced.
The fuel that worked best was 20% nitro, 50/50 castor/synthetic, 11-8 Master Airscrew prop.
If you use it, make sure it has plenty of cooling air as it tends to run a bit hot. Also, make sure it breathes outside air - it likes cool intake air.
It met its demise when I belled it in in the bottom of the hourglass. When the engine hit, it tore the lugs off the case!
It's a good engine - give it a try.
Bob Z.