When I installed a B20F in my ’52 PV444, I found it necessary to drill new holes in the crossmember. Fit 544/B18 mounts to the engine and measure what the distance between the holes will have to be. Do this with the engine almost in place. It may well be you’ll find the new holes will have to be too far apart for easy access (I did).
I solved it by using my original B4B-mounts, of which part of the brackets was cut off. The remains were welded onto (part of) the brackets from 544/B18 mounts. But even in this case, drilling new holes in the crossmember was necessary.
It might be that B16-mounts supply an easier solution, but unfortunately I don’t know the differences between B4B- end B16-mounts in detail. Hope this helps anyway.