I did the same thing when I went with the TFS cam, used trick flows spring upgrade kit. If you do that then you can upgrade bumpsticks later down the road if you want!
Matt
yea i just put tfs1 in my 89 gt love it... if i can get it to idle right its got a bad problem with surging idle and often so bad it stalls. i reset the tps helped a lot but i think its sucking air throught the non functional egr valve
The Explorer 5.0 cam had .422/.448 lift and the Mustang was .444/.444 lift. Even with 1.7 rockers a decent set of factory springs will be up to the task.