Not a slant. 1947 boat Engine

Take the spark plugs out and squirt some oil in the cyls, to lube and to help seal the rings for compression. Then spin it on the starter to
get excess oil outta cyls preventing hydroloc .
Check for spark, install plugs, check fluid levels, prime carb, cross fingers, go for it .
If it fires, check oil pressure, monitor engine temps .
Good luck .