391FT to 428 or larger?

Hi,
I came across a 1970 391FT today, and am considering buying it for the core to overbore it... Is it possible? I know that ford sold bored 391 castings as replacement 428 blocks. What would I need to do? Can I drill the engine mounts on the side of the block? What about the timing chain cover? I can pick up the engine and 5speed trans as a unit...(I want to put them in my 68 f100 shortbed to retire the 360 and t-18 that are in there now).
Thanx