70 Olds 350 Redline

[smcurro]

Hi I have a 70 Olds Cutlass with the original rocket 350 and th350 trans. The engine has around 115,000 miles on it and to the best of my knowledge it is completely stock and has never been rebuilt. The car has a 3.55 posi and at highway speeds the rpms are 3000+ (3000rpm at 55mph) in the top gear. I drive 50 miles a day 5 days a week with this car and I notice it burns a good amount of oil. I always make sure there is enough oil however and I check the level weekly.

My questions are:

Am I in any danger of damaging the engine with a constant rpm between 3500-4500 for a long time (more than a half hour)? What is the highest safe rpm for this length of time, 4500?

If I wanted to drive a long distance (300+ miles on the highway in one shot) would this be safe for the engine or is such a high rpm range (3000-4500) for such a long time dangerous? What is the highest safe rpm for this length of time, 4000?

What is the highest safe rpm for an engine in this condition for around 15 seconds, 6000?

Finally, is there any danger that burning oil will damage the engine? (other than low oil - I always check the level and I never let it go low)

I am currently more or less broke and I also don't have the means to do any major engine repair. This is the only car I own so you can see I can't risk any damage to it. I have owned this car for two years and it has yet to give me any trouble besides a burned out starter solenoid. I want to be sure to keep this great car running strong. Thank you very much for any advice you may be able to offer me.