News on my build
Got Transgo kit for the 650 series trans, also ordered spare valvebody from mate. Plan to order new gaskets, rebuild the spare valvebody with the kit, then go fit it to my transmission
Also found super rare Tom's ECU for 20 series celsior for quite reasonable price (under $300), the problem is it's listed for sale in some online shop in Tokyo. Could find one guy who agreed to talk to them , can't wait for the results.
If I didn't want to retain the hydro fan, GS400 ECU would be way better substitute for stock ECU (it offers paddle shift operation on the trans, and has no speed limit). Tom's ECU however is at least different to what anyone else has