[SFfiredog]

First, let me start by saying my wife is from Australia and I had the pleasure of visiting friends in NZ while "down under". New Zealand is one of the nicest countries I've ever been to. Absolutely beautiful and every person I met treated us like friends and family. Lots and lots of car people and the vintage warbird scene is one of the best in the world.
I have built 6 engines with Schubeck flat tappet composite lifters and absolutley love them. I can get really aggressive on the lobe design, almost approaching roller cam lobes, using a flat lifter.
Maintenence is almost zero, the engines go thousands of miles without even needing a valve adjustment. I can run much higher spring pressures, 160 lbs to 190 lbs on the seat. Those pressures would kill a regular lifter, and the composite requires no break in.
If you want a roller lifter, Schubeck makes what he calls a "Roller X" lifter that has the trunion and roller made of the composite material that uses no bearings. These are not the same as the radius lfters tha Schubeck sells. The Shelby block is not really friendly to a "dog-bone" style lifter because there is no room to mount the stud that holds the lifter plate in place. (the lifter galley bracing gets in the way) This would hold true for the Jesel "dog-bone" lifter as well. You will have to run a "link" roller lifter. The Jesels are excellent but very pricey. I have had good luck with the Crower "hipo" pressure fed lifters.
I have built a few Shelby block engines and just took delivery on a new Robert Pond Aluminum FE block. It is really nice.
Let me know if I can be of any help.
--Mike