Looks your engine is pretty much complete for the custom or drag version minus the fan belt, fan, and generator (delcotron)
according to the instructions !
https://public.fotki.com/drasticplasticsmcc/mkiba-build-under-c/amt-instructions/automotive-cars--pi/buick/amt_1963_buick_rivi/1963_rivierra_amt_2.html#media