Quote: i like the x mainly because its production looking up top,and racy down low...plus roller lifters pop right in it... plus i am old and like old stuff lol
The R1A does not have the filled in valley like an R3. Here's a pic of one. They do have the meaty lifter bosses though and the 18 bolt head provision. It would be real nice if the 59* version could get an 18 bolt delete, so you did'nt have to deal with the bosses for rollers. So if you wanted an 18 bolt block it would be 48* only.
That is what I'd make, 2 different versions:
59* 340 main, 4 bolt, with 360 oil pan provision (so you can either bolt on a stock 360 style pan, OR if you already have a 340 style pan, you can use a pan rail spacer which are now available for sale) 9.610" rough deck height, so you don't have to deal with 9.560" deck BS with off shelf crank/rod/piston combos that are all designed for 9.600" deck height. 3.91" rough bore. This block would be for 10 bolt heads only, no extra bosses. I would plunge cut the lifter bosses to Std. LA height, so any V link bar roller lifter should drop right in with little or no clearaning. Standard 59* cam tunnel of course.
48* 340 main, 4 bolt, 360 oil pan #5 cap, 9.610" rough deck, 3.91" rough bore. This block would have all 18 bolt head bosses drilled/tapped from Chrysler. Any 48* Mopar or Chevy spacing .903 roller lifter would fit with no mods. The 48's should already have an .125" oil feed hole in the lifter bore like the new AC Part # R3 blocks, so you don't have to buy/use the cheesy MP 48* lifter bore drill tool. Standard 48 degree babbit cam tunnel, and should come with a new set of 48* babbit bearings in the crate with the engine like the R3's do, so you can avoid panic like Kammer & Kammer had when they did Rick's 48* R1A and the 59* cam bearings did'nt fit LOL
plus i am old and like old stuff lol 
