First, Ken is an AWESOME guy and has been spot on with the recommendations he has made for the 4 cams he has ground for me - two were against what I thought I wanted & I'm SO happy I listened to him. For the last two, I just shut up & listened after giving him the engine specs.
Now, to the OP's question. You said..."It's a roller cam I'm reusing the original lifters." Then above you say he told you to regrind a hyd roller into a HFT? I'm just questioning your use of 'flat tappet' and that you're sure you & Ken are on the same page? Or are you saying Ken wants to regrind your HFT core into a hyd roller? Sorry, it's really late & I need some sleep.