Make sure the flywheel imbalance is correct!!!
As mentioned above the 351 has a 28 oz imbalance and the foxbody 302's have a 50 oz I think it changed it 79.
I know for sure you'll blow your tranny if it's an auto tranny
(from experience I blew a AOD you shoulda seen the torque converter after)
So I learned my lesson the hard way.
I wouldn't suggest risking it, If you have a AOD you can find the proper flywheel from a 80's full size truck that has a 351 AOD combo, You'll wanna grab the starter from it as the 2 flexplates have differant tooth counts. Might be hard to find but it might save you some dollars. If your short on cash you can also find a dual hump oil pan in old grand marquis ( for sure) or crown vics (I think they came with 351's) But dont cheap out by a new pick up.
Ive used stock motor mounts in one of my cars and still managed to get one of those little triangle edelbrock air cleaners under my hood no problem, any more than that and you'll need a cowl.
I used convertable mounts on my latest build and I have room for a huge chrome ford racing assembely, So definatley go for the convertable mounts.
I bought a spec adjustable balance flywheel for my 4 speed so im sure they have one for the t-5 but havn't done that build.
The bellhousing will bolt right up to all sbf's and even 351 C's it's the imbalance you need to worry about.
Besides that you WILL need to purchase 351 swap headers, I have a set of bbk's and MAC's they both have a nice finish and were a decent price. Ive went with shorty's both times so can only speak to there fitment, which lines up with stock 5.0 X or H pipes or stock exhaust.
I would look into a stand alone dizzy to get rid of that SH**y expensive stock spark box.
Ive used a cheap pro comp dizzy one one of my applications and it works just fine, doesn't have the best reviews but I havn't had any problems with it and it's real cheap.
Overall it's really not that bad of a swap, I am no licensed mechanic and have done this swap several times. Just have the parts you now know you need and it'll go smooth.
Here is a excellent link for the swap 351 Engine Swap - 5.0 Mustang & Super Fords Magazine
Good luck and ANYONE willing to add more or correct me please do.