cast crank to forged in 440

well I have a steel crank that is an 8 bolt flange an has the pilot hole already for the 4 speed that I have , the cast crank does not have hole drilled for 4 speed , which leads me to my dilemma of the swap , my 440 was rebuilt from a motor home with low mileage , cam was replaced with comp cam , unsure of size but is mild from what I was told , the heads are done but are 4006452 but have access to better heads , and new rings on std pistons and new std bearings on the crank ,,,the 440 will be for street driving

Be careful with that. Most of those do not have a crankshaft register to locate a flywheel properly.