Safe, when applied to race motors, is a relative term.

Nothing above stock limits with stock motors is really safe.

But some specifications are likely to induce breakage sooner than others, and some will run longer without the need for teardowns.

Homegrown, you sound like with your varied program aimed at just a few events you would be a candidate for building hand grenade motors. The drag race guys can get 5,000 HP out of the big V8s. Of course, that is good for one pass. How long do you need your top speed ice course engine to run to do the job?

Keep in mind the '75-'76 3.0 Carrera had red line of about 7,200 (SC cams).