Look, it might seem like a simple question.
But it quickly branches out considerably.
An answer that’s detailed enough to be helpful becomes long, and has been done already.
The more effort a question takes to answer, the fewer answers you get.
Anything that makes the question more specific makes it easier and faster to be helpful.
Like are you OK with bar end shifters?
Friction shifting?
Does it have to be brifters?
How many speeds are on the bike?
Would you consider swapping out the rear wheel?

I’m INVITING you to ask, only to use a format that’s easier to deal with. If you want to interpret that as all-out criticism, I can’t stop you.