wrench 87 the springs are your choice. When the head work was done they should match the cam profile, compression, rpm range for power. ( tork band and HP max rpm range ). What rocker arm setup are you running? Alot of guys run comp cam springs with a dampener. They have about 140 closed pressure and 450 lbs open. What lifters are you running solids or hydro rollers? I am running a 587-607" crane hydro roller. I run the beehives that are for the BBC motor #26120. These springs are good for only 600 or 625 max lift. Have run them for 2 years and no problems. I limit the motor to 6,000 rpm when it was the 452. This was with a hydro cam at 501-533" lift. Before adding the beehives the motor would nose over at 5,700. After the springs where replaced and the adjustments on the pushrods set for .015" of plunger depth, the motor would spin strong to 6,000. Comp saids there is a 300-400 rpm range gain because of the 44 grams per valve that is removed. I am still running the same heads but have added a stroker kit from Barry R. The cam I am using is the small crane hydro roller. I didn't have the motor broken in yet but up to 4,500 rpm (limit in MSD box) the car pulls like a train. I will have a max rpm limit of 6,200 rpm but could spin the motor to 6,500 without it noseing over. I couple stories have been done on these springs that caused failures to the motors. 2 where about IMPROPER assembly and haveing no spring clearance between the coils. There was coil bind and it breaks the springs everytime.
The other was a race motor with titanium valves and turning 7,400 rpm. There where picture of the damage. I think the valve broke( it was on the exhaust side ) not the spring. Comp has a spring that works for .750" lift cams. # 25595. They say it is for Nascar. Anyway they are not cheap but they work for my applications. There is a real 10-15 hp pickup in the upper RPM range. I got this off the dyno on the 452 motor. These spring are better at stablizing the valve and valve train. 44 grams may not seam like alot but put in the right application, and that motor spins up just a little faster. With the heavy valve train in the FE, any weight saved will help. I am looking at building a rev kit to take the load off the valve spring. This should give another 500 rpm and help stablize the valves even more. The lifters are heavy when they are hydros and not solids. Good Luck Rick L.