Rocky Jennings modified the WBX case for air-cooled, made the oil-filter housing that allows me to mount the stock oil cooler in the doghouse, and modified the lifter bores to accept SBC-diameter Isky RedZone roller lifters (which he also modified). The lifters have a flat machined onto the body and guide plates index the lifters. That's as much as I'll say about the modifications for the roller lifters...if you want to know more, call Rocky and put in a deposit for a case
The converted WBX case has a very tall deck; this required that I find head studs that had a lot of thread cut on one side so that I could shorten the studs by 0.7". BugPack's chromolly studs were the only ones I found that fit the bill. Stock, Raceware, or ARP all would've been too long and would've not had enough thread. I also had to have a set of cylinders turned down about 0.700" to set the deck. Even with all the work that Rocky did on the conversion, this is not a bolt-together set-up. You had better do your homework and, ultimately, know what you're doing.
The real issues with the roller conversion revolve around the valvetrain. Because this is a daily driver, I stuck with the 044 head casting. This limited me to only VW-diameter valve springs. If I had run Comp Eliminators, I'd just run K800's and be done with it.
I located the stiffest VW-diameter springs I could find: Crower 68311. These are a Vasco Jet H11 material for SBC (1.270" diameter) and fit into the VW spring pocket. I'm running Crower's ti retainers and chromo keepers that reduce the installed height by 0.050" (thus, less shims needed under the spring). I'm running these with CB Performance RaceMaster valves...these are about 0.200" longer and use a Chevy keeper. The 68311's set-up with about 430-440 lbs of pressure over the nose (Crower actually makes this same spring in a PacAlloy material which pushes 460 lbs...but they cost $120 more than the Vasco Jet material, which is already around $210 for a set of 16).
Because I'm arguably under-sprung for a roller cam, I'm also running aircooled.net's aluminum pushrods. So far with this combo, I've pushed to about 7250 rpm without valve-float.
The rockers are Scat 1.4:1. I decided to run these without lash-caps because the rocker studs are not long enough to run 'em and still maintain proper geometry (remember, the valves are .200" longer). The valve tips must be pretty hard because they have begun to wear a groove into the pad of the rocker arms at less than 1000 miles. I'm probably going to replace them with Pauters and get rid of the last of the Chinese-made parts on this engine.
I'm also running Pauter pushrod tubes, which are much larger in diameter than JayCee's. This allows the big end to seat against the case and provides plenty of clearance for the very tall roller lifters. The small diameter of the tube seats against the head just fine...no leaks so far.
The Type 1 oil cooler sits perfectly in the doghouse. 