I have a pre-ban (purchased new 1993) Colt Match H-Bar with the A2 non detachable carry handle receiver. It works great and is sub MOA with the factory peep sights with good ammo from the bench if I do my part. However I want to mount an optic with back up folding front and rear sights.

Which manufacture of flat top receiver do you recommend that are compatible with this particular Colt?

I also want to replace the hand guard with one that is free floated. Any suggestions?
Thanks.

You'd want to look for a rifle upper, one with no feed ramps.
There's a Colt in grey on the EE right now, I think?
Would probably match your lower quite well (not mine, search Colt on the EE, should come up?)

As far as free float tubes, you could run from a cheapie on ebay for $50-60 all the way up to
a PRI for $300+ iirc.
Taste and wallet would come into play.
Shame you are breaking up the upper, have you thought about just buying an assembled one
and saving the original?

What is the EE?

This. With what all it will take to get to where you want to be, I think you will be aggravation and money ahead to just put together a whole new upper. The Colt complete A2 upper would be desirable to someone.

Or honestly, with the price of parts right now, put together a new lower to go with it.

why not just mount a carry handle rail

the "equipment exchange" on this site.

It's your rifle so your choice/decision.  However, I would caution against replacing any parts on that gun if you think that you or anyone in your family down the line will ever sell it.  Anything other than putting another complete upper assembly on the gun and retaining the original so that you can interchange or easily restore it back, will significantly destroy it's value.