Older 530 series

I have two cars which I have liked very much, a BMW 530i and a Datsun 280Z. They are both 1977 vintage. The Z has always been a dependable, fast car -- it will actually outrun the beemer -- and I drive it the most. The Beemer has been garage kept, but twice now, I have had head problems with the 530i. Are these heads inherently weak?? The head has cracked twice on me, but this last time it cost me dearly. Glycol got into the oil pan and I spun a rod bearing. I have been told that 735 heads will fit on the 3.0 liter engine, but I am toying with the idea of putting something else in the engine bay. Any suggestions?? I am not as familiar with BMW's and what is available as I am other vehicles.

I have leased a G35 Infiniti and I am leaning towards just getting rid of the Beemer, even if I just junk it. I love the G35. It handles so well and is very fast. It is fastly becoming the car of choice for me. I am beginning to like my S-10 pickup truck (4.3 liter and hopped up) more than my Beemer.

Any suggestions on what to do with the 530 would be appreciated.

Thanks...

eti engineer