You can re-use the stock 302 mounts, as the mounting pads on the blocks are the same. Most reccomend switching to the '90- ish convertible mount, as it is a stronger design and also lowers the engine for better hood clearence, which your going to need with the 351.
The
tranny will bolt up fine, as all '65 and up 289, 302, 351W, and 351C's, as well as 3.8 V6's use the same bolt pattern.
You can use the Cobra upper, but you will need the lower from a '93-'95 Lightning. (Same as the Cobra/GT40/Explorer lower, just designed for the 351W.)
You will also need 351 swap headers, they are availabe in shorty's, equal shorty, and LT's from BBK, MAC, and FRPP to name a few. IMHO, the BBK shorty swap headers are the best bang for the buck.
And lastly, you will need a 351 swap power steering, or A/C/PS bracket to run the all of the Mustang accesories, which is also available from FRPP.