This is just my Opinion and does not answer your question.
But If you already have a fatman mustang II frontend (as you say for sale) "WHY" would you go with 70 year old technology with the stock front end????
In over 30+ years of rod building I have only done 1 car with the modified stock front end and have done dozens with aftermarket front ends like mustang II,volare' and dakota.

again,just my opinion but I think the mustang front end would be the better way to go
it may take a little more work to do it but it has so many more options in brakes, A arms, rack and pinion, springs and air ride over the stock style frontend.
Good luck in whatever way you deiced to go. Ron....