Welcome back to motorcycling @bjr55
You've been a lot more practical and sensible than me, jumping straight on a 1200 after 24 years.
However, it's the fear that keeps us sensible, and a having a good motoring mindset that keeps us from killing ourselves, whether gripping handlebars or a steering wheel.
I had a souped up Renault five try to race me at the weekend, I was quite pleased with myself that I just didn't bother and I let him roar off down the road. On a bike that could do 180, the only thing I have to prove is that I'm not that that stupid.
With your obvious good attitude, you'd have no problem with a big bike, as it'll only go as fast as you make it.
The very best of luck to you.