While the 413 was a good engine, and it is an "RB" block, like mentioned above, it just doesn't have the bore to be able to accept huge valve aluminum heads...
To try and bore one out ot the popular 440 bore, would be junking the block...you'd be better off IMO, building the 440 you have...
Pistons for the 413 are high as hell too, because? you guessed it, NObody fools with 'em...