High Colin,
I had oil pressure problems as well until I went to 50 weight valvoline. I utilized the HVX mods to my engine ( these mods push a lot more oil to the heads) and when it was hot it was bad news. I tried everything and after I started using the 50 weight I had no more problems. I had gauge issues as well. Check out my pictures. Of course you must preheat, a lot, in cool weather.
One reson oil pressure is a prblem in these engines is the crank is ground to the lower limits of tolerance and it makes the engine loose. This is for the kiddie or dune buggy crowd. I measured mine with micometers and dial bore gauges and found it was right at the lower limit.
I'm running a ellison throttle body injector mounted down underneath and have never had any issues with carburetion. I installed a pump for takeoff but my engine will maintain full power in the climb without it. When I get to a safe altitude I turn it off and cruise along.
I am very disappointed in my climb performance and I have had some head trouble due to some machine work not being done like it was supposed to be. I also put on a new set of heads from Great Plains because I pulled the sparkplug threads out of the original ones. I started having valve trouble at less than two hours later and at less than 10 I was torn down. I pulled the heads and the valve seats were never done properly and the guides were bored oversize. I emailed Steve Bennet and he said to send them back but no mention of who was going to pay for the freight. I also did not want them ( his supplier) rebuilding them after what I received for new. I have my own valve equipment and I'll fix them myself.
I worked on putting it back together today and I'm ready to put the cylinders and heads back on as soon as I get my cylinder spacers. I have made some changes that should make my performance better. Stay tuned, keep in touch.
Wayne