IMO i would make them all the same, i would feel uncomfortable putting two different lifters in. but im sure .048 doesnt make a big difference. just make sure you adjust your rocker properly just to make sure you dont get a tick.

 

Your pushrod shoud be .050 shorter IF it was the right length before.

Place new lifter in the bore.
Place the lifter bar down to hold it still
Bring the cam onto the base circle
Put the push rod in
plave a light coat of grease on the valve tip
Carefully (without taking the grease off the valve tip) install the rocker.
Bolt it down without any shims.
If the lifter cup collapes .030-.040 and the roller on the rocker tip in on the center of the stem you are good to go. If the lifter goes deeper add shims until you get it right. If the the lifter cup is up against the snap ring or the roller is moved to the intake side on the tip of the valve then your pushrods are to short.

Of course an adjustable pushrod length checker would be faster but this should get you in the ball park. Just remember Lifter cup .030-040 -+ and the roller tip on the center of the valve.
Let me know what you find. With the right lifters I bet you are pretty much spot on when they go on without the shims.
install th

 

Again thanx alot man!! i'm pullin it back in the shop this sunday and puttin it back together.. i'll let ya know..

 

Instead of grease on the valve tip I used a magic marker. It worked alot better than grease. You got them lifters from Ford?? Bet those were expensive.

 

Install the FRPP replacement lifters and make sure you check for the proper valve train geometry (which includes determining what length PR's are needed).

 

actually the guy i bought the car from had them along with a pretty good list of other parts to sell with the car. which is also a reason why this problem is occuring, cuz i bought somone else's project... if you only knew how much of his mistakes i've already fixed..