Where do I start?

Definitely keep the rockers. Funny, I have a new 68 340 hyd cam sitting in my original 340. Put it in the motor and then never finished putting it together. Installed another motor so I didn’t have to worry about the original block. Will never use it, not a “stock” specs guy. Plus not a fan of hyd cams. Bought it back when I was young and foolish, now that I’m old and foolish solid flat tappet guy or solid roller.