Yes loosing spark when heating up is a good indicator to me for this. Electrical circuit expands with the heat and gap/break in the circuit occurs. When cools down works fine gap/break is connected and operating.
600* is normal operating high speed temp of this type of engine on the exhaust...
When I did my rubber hoses I took my Burby to work and and parked it with the front end right on the edge of a loading dock. Still a major bitch trying to access those nuts but better than laying on the ground and getting a better angle of approach.
I had one quad light Ramcharger that was 2 tone green with a green interior, that was a rare bird. No pics of that one. Here is the '78/9 with the 4" lift before I put the body lift and 35's on it:
And my '86: