318 safe max RPM?

Any one have a recommendation on a relatively safe max RPM for a 318?
71 318 stock bottom end; stock cast crank; stock heavy floating rods (the 340 type) ; stock pistons.
New rings and barrings. This was a very low mile engine. I was thinking 6,000????
When I was a kid I know my 73 318 saw over 6,500 many many times. Not saying it was smart.

I know I have the top end and cam to pull it, gust do not want to go past what the bottom end can take. Thanks!