For a 235 I wouldn't turn over 2500 rpm for long periods of time. So you'd ideally like to keep your rpms at 2500 (or lower) at 70.
There have been lots of discussions in the past on adapting the T5 5 speed tranny to the 235. And someone out there makes an expensive adapter plate that allows a direct bolt up. On the flip side there have been questions raised about it's durability and mixed opinions.
Bumping up your cruising speed is great. It'll get you good attention on the freeway. Just make sure you can
stop. A
thorough inspection and rebuild of your braking system wouldn't be a bad investment.
I'm glad I don't have this issue with my '66. Even with the 3.73 rear gear the 230 still manages to hold 60-65 mph for hours and 70 for short stretches. I can't wait to get the 89mm in with its .73 overdrive. I see 75-80 mph cruising in the near future.
