Ignoring the ford fanboy within that wants to hit you with a 2x4 for considering this:
Dunno how the two engines compare in size, but 66 mustangs don't have much room. In 66's 351w's and 351c's are notorious for having hood clearance issues with tall intakes and need special swap headers; big blocks are a no go without removing shock towers (big job). If the 327 is a bit shorter and skinnier than a 351w, then it could work. You should look at the types of intakes and headers chevy guys have to use in tight applications (I don't know of any examples at the moment, but I'm sure they exist). But to answer your question, no, i don't know where you'd get the motor mounts.
Transmissions back should be easily doable... get a chevy bellhousing and a tremec or t-5 could work, or a powerglide or th350/400.
66 Coupe, 351W w/ T5 (CF Dual Friction, Fidanza flywheel, Pro 5.0), Trick Flow heads, XE274H cam, Stealth, Holley 670, Heddman headers, Flow 40s, MSD 6A, Pertronix Ignitor, KYB Gas-A-Justs, 4.5 rear leafs, 3.25 9 inch Trac-Lok rearend, sway bars, shelby drop, fuzzy dice