I'm curious (sorry if someone asked) Your block is made to use a roller cam, OEM lifters can be bought for $100 a set (ish) and the cams aren't that expensive.. why a flat tappet?
P.S. just read bout the noises... hope it's not serious :( Perfect block for a stroker though :)
The engine when I got it still had hydraulic flat tappet and stamped rockers. So I just went with another flat tappet. But I started the engine back up and it didn't make the noise until it got warm again. It definitely sounds deep. This sucks.