Correrct. Any 160 cid crossflow powerhead will bolt up to your 235 adaptor plate in the midsection. None of the 149 cid powerheads with the flat exhaust plates will bolt to your 235 adaptor plate. The driveshaft isn't the issue, it's the way the exhaust is routed on the 160 cid blocks & midsection.
Basically any powerhead that has the same exhaust (bubble back) as yours will work.