351 to 460 swap/ need engine mounts

I have a multi vechile project of which includes a 77 ford 460 with the 4 bolt to engine mount and a male stud to frame mount. The 351 that was in the 78 bronco FS had a 3 bolt to engine mount and a female to frame mount. At any rate, the conversion mount I need does not yet exist, I am wanting your thoughts on wether to fabricate a set of mounts or atempt to obtain a set of frame to engine extentions from a FS bronco that has/had the 460 installed.?