Morell Hydraulic Roller Lifters

I have a 340 in the machine shop. They have a set of retro fit Morell hydraulic roller lifters that someone backed out on. They are fixing to return them.
My plan was to reuse a good hydraulic flat tappet cam and lifters from a different block. The machinist is a little skeptical on me re-using them. He said no way on a chebbie but maybe on the Mopar. I have a set of new Promaxx heads set up for... a flat tappet cam. I'm thinking I can get these roller lifters for 500 bucks. My question to the masses is this.
If I buy these lifters, can I run the springs on the Promaxx heads that I ordered for a flat tappet cam on a mild roller cam? I'm thinking 22O or so @ .050. Half inch lift.
Hydraulic Flat Tappet .575 max lift
Closed ………………….. 115 lbs. @ 1.800”
Open ……………………. 310 lbs. @ 1.225”