I've just started gathering pieces for my 393 project
If you want to run a hydraulic roller, the best way is to get your hands on an F4TE block. This has the taller lifter bores and is tapped to accept the lifter retainer, stock link bars, and roller lifters.
I've got a decent set of GT-40's that have been worked on by Fox Lake. They do flow enough air to support 475 N/A horsepower so I will use them for now but they will be upgraded at a later date. They may not be ideal, but these heads will make more power on a 393 than on a 302-'nuff said. I'm not a fuel injection guy so I'll run an RPM air-gap manifold and won't have to worry about long runners choking things off. As far as headers go, there are enough other mustang guys out there wiling to buy a used set of headers so it's pretty easy to dump them off, then just buy a new set. I'll probably try and trade the cam to someone who's bought too big of a cam for their 302 but we'll cross that bridge later.
If you can't find an F4TE block, don't be afraid to just use a hydraulic flat tappet cam, there's nothing wrong with them and you can still make big numbers.