[Mike Taylor 3601]

Break in like any other flat tappet,make sure you don't have too much spring pressure for break in,less than 300 lbs open.
use a oil with high zinc,like Gibbs or Lucas break in oil also
If you can get lifters w/ .015 plunger travel will work better Precision products performance center in NC has tool steel version for around 450.00 set.
How much spring you need depends on how agressive of lobe you have, how much rpm
going to turn.
926 spring I'm guessing you have Comp stuff since that sounds like comp part# ,if is comp do you know who you talked to? if is'nt comp who's is it?
Mike Taylor 3601