Get yourself a stroker and never look back. I've got a 2332 in a split bus and it is fabulous. And even here in Spain it doesn't overheat - but had to make sure that all cooling was as stock, plus an additional external oil cooler.
The limitation however it the bus itself, or maybe the steering box with a load of play - I can't cruise at 120km (approx. 70 to 80mph ish) for any long periods of time - too much stress on me and the bus. Took it up to 140km/h the other day, and although it had no problems getting there, I could only maintain that speed for about 10 seconds - sweaty palms and a racing heart rate brought an end to that. Fitting a pair of adjustable Konis Classics to the front end has helped stabilise it a lot at high speed. Next step is to do the same at the back plus fitting yet another refurbed steering box.
Make sure that your suspension, steering etc is as it should be before investing in a stroker, otherwise you won't be able to use it. However, you may have to accept that due to 100 year old steering technology, narrow high profile tyres and a bread-bin shape to the bus, it's never going to keep up with modern traffic. Would be interested to hear from those who's bus can??