what dictates which one to use?i will be using the 10 degree locks on a 383 hi po street eng.thanks

As you know the # of lock grooves would need to match the # of grooves in the stem & the lock degrees would need to match the retainer degrees. You have the valves & need compatible locks/retainers?

Also the stem size.They do make different sizes.Rocky

I guess the first question should be....... Do you need 10deg retainers and locks?

In addition to needing the correct locks to fit your valves, 10deg locks require the use of 10deg retainers, and the retainers have to fit whatever springs you plan on running.

Comp Cams has 36 different part numbers for 10deg retainers.........It's not one size fits all.

What RPM and how often are you planning on running the motor up to this RPM ?
If you have a camshaft that has unstable lobes on it you want the best locks and keepers money can buy, if you select a good cam with good stable lobes and not taking it past 7000 RPM all the time then the stock parts will suffice

CAB or ? define stable lobe, please?

This post helps me as ive never built near stock or budget stuff but im working on one now, a old purple shaft .500 solid dirt track cam and have questioned if I can get away with oem, although new retainers,ect...

Maybe 6k rpm or a hair more, nothing more then a stock 340 would see.

Since the op-s question has been answered, I might as well ask, how are the old bar bell style solid lifters for use in what I described above?

They are about 1/2 the cost of a comp 821 solid.

A unstable lobe can and some will cause valve float from 4800 RPM and above, Some lobe designs do it later than other do
If your motor is eating up the top of the valve stems needing constant valve adjustments or wearing out the valve springs, keepers and retainer you more than likely have unstable camshaft
IHTHs
Most motor problems will talk to you , under standing what they are saying sometimes is the hard part

Call Racer Brown. The guy probably has the answer. Isn't there a number on the box?

Here's a guess:
Your camshaft is at least 30 or 40 years old and probably has around 240 degrees duration at 50 lift. It probably has a symmetrical lobe shape. A circle track cam has to run for long times without maintenance.
From those guesses I would be very sure that your camshaft is pretty stable. 240 duration at 50 is a loooooong time to open and close a valve 1/2" For example of a new "modern" cam, Hughes gets 0.503 lift in 220 degrees at 50 lift.
My guess is you are going to find this cam won't need a lot of valve spring. For safety you may try loading the valve with spring force at the upper end of solid flat tappet cam requirements. I am also guessing your valve lash to be 0.025".

R