Camshaft Bearing Cap Failure

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Building a D15A3 engine with dual Weber carburetors for my '87 CRX. I just had my second failure involving the Camshaft and Camshaft Bearing Caps. On the first Head, once we got the engine running, after about 15 minutes of total run time, the engine starting making a squealing noise that we could not identify. Soon thereafter the Camshaft locked solid, causing the Timing Belt to snap. I assumed that when rebuilding the head I must have mixed up positions of a couple of the Camshaft Bearing Caps resulting in a misalignment of the Camshaft and the Camshaft Bearing Caps.
A second Head was build for the engine. This one was put together by a machine shop which specializes in automotive engine repairs and builds. The engine with the second Head was run for about 15 minutes, a couple minutes at a time to adjust the carburetor settings. When I took the car out for a test drive, after about 10 minutes of driving up and down the road, the engine quit running. This time I found that the Camshaft Gear had sheared off the end of the Camshaft. Upon teardown the first Camshaft Bearing Cap was found to have galled and seized the Camshaft leading to the Camshaft Gear twisting the end off of the Camshaft.
Searching for the "Why" of these Camshaft Bearing Cap failures has lead me to consider and possible oiling problem withing the Block and Head. I am using Royal Purple 10W-30 Break-In Oil. When initially started the engine has 50-60 psi oil pressure. After warming up the oil pressure at idle will drop to 3--40 psi. When warm, oil pressure is in the 40-50 psi range while on the road. This is the oil pressure in the Block. I have no way of measuring oil pressure in the Head.
Could my problem be an oiling issue with the Block to Head connection? These were two different Heads so it doesn't seem likely that any oiling issue would be in the Head but it could be something common with the oil flow from the Block to the Head.
Has anyone every had to deal with this issue and if so, how did you correct the problem?

20230728 Broken Cam Shafe 1.JPG
20230618 Wiring in Engine Bay 1.JPG
is something hitting and causing a hard-stop inside? any indication of it locking up? valve hitting a piston? did you clay the motor? probablly wasn't necessary with a stock head... thinner head gasket?