I hate to say it, but this is Not a bike you can easily upgrade. You can fit a seven-speed cluster on it, and seven-speed brifters (that's what have on my '83 Cannondale) .... But ...

My friend, I think you need professional help.

Seriously .... it sounds like the bike is not at all sized or set up for your body and your riding style, but to try to explain and understand the myriad and interrelated possibilities .... A person would need to measure you thoroughly, and /or watch you ride, and then figure out how you like to ride or want to ride.

A lot of bikes are set up in race configuration, with the bars well below the seat and well forward, which strains your whole body but generally hits the hands first. And your bike is a racy bike to begin with.

Whether the bike could be adjusted to fit you can't be determined from a distance. And in order to bring it as up-to-date as possible would take a few hundred dollars at least, and you still wouldn't have high quality or many options.

Really nice frame, sort of .... just not much can be done with it. You can play with raising the handlebars .... but pretty sure that eventually you are going to buy a newer bike, so I'd suggest not spending any more money on this one.

Maybe you can sell it to some Classic and Vintage aficionado. (https://www.bikeforums.net/classic-vintage-sales/)