Lobe taper is a very important consideration---with rollers the cam lobes don't have any base angle to rotate the lifters and then of course without that taper the cam doesn't want to stay BACK in the cam tunnel ----It requires a thrust plate and oiling mods to lube the front gear/block area and without that the load from
oil pump and distributor drive will cause the cam to move forward and backwards---this will also then wipe out the gears as the mesh angles don't remain correctly constant-----
I also once modded a Holman-Moody marine block with 16 -3 tubes to the lifter bosses so I could put a hydraulic lifter cam in it for my 1966 Comet GT390------but before I got it together they came out with the 428CJ and I was able to get one in a Torino------it ran so good that we then put the 427 ( now also with a 428 crank ) into John Keelings 1969 Ford F150 plus 3 dueces and CJ hood scoop for our dragster push truck---ran very nice and did it ever come on good when those 3 dueces opened on the fire up road-------