You can use motor mounts for an 86 V8 302 Mustang with no modifications to the stock 54 Ford chassis mounting brackets. You can cross Anchor 2725 and Anchor 2726.
The AOD will sit on the stock '54 trans cross member using the ANCHOR 2253 mount
You also need a front sump oil pan to clear the crossmember. Most SB V8 Mustangs from the 60's and early 70's had front sump pans. So an oil pan for a 1968 Mustang 302 will work nicely. Spectre pans have a nice oil baffle in it. To complete the conversion you'll have to get a matching front sump oil pickup/screen.
Changing to a front sump oil pan creates an issue with the stock oil dipstick on a late model 302. You will need a timing cover that has provisions for an oil dipstick that goes down into the front sump. Again, the 1968 Mustang 302 Dorman cover (part # 635-107) with the gasket and front seal will do. These are available just about antwhere including eBay.
There are a variety of solutions here. There is a whole bag of worms here. First - early SBF(pre-69) cranks are 3-bolt. The later(post Mid-69) are 4-bolts. Then you have early V-belt drives(pre-90) and later flat serpentine belt drives. Then you have to decide how many sheaves (grooves for belts) you need. You can have as many as 4 on some v-belt applications. Serpentines may have 2 but usually just 1.
Front grease seals part number 472319 fit the hub and spindle. Hope this helps anyone with this same problem
You can mount a 55 gas tank in a 54 with very little effort or mods HAMB