Knowing the Record very well (having sold a ton of them when they were new), I can recommend upgrading the bike . . . . . . . . . say, to the level of a like year Raleigh Super Course. Definitely upgrade the wheels to alloy rims and quick releases. That's your first step. Derailleurs are second, as by modern standards (say the modern-ness of 1976) the Huret Allvit was not only well beyond its sell-by date, but was probably the poorest performing derailleur available back then. SunTour V is a nice idea, a Huret Svelto might be a nicer idea, works just as well, and you can keep the shifters and still keep everything within the marque. The front derailleur works just fine, replace it only if you really want to match the rear (it already matches the Svelto). Alloy bars instead of the stock steel ones will save a bit of weight.

After that, the costs start picking up and the upgrades start being a bit less cost effective. A cotterless crank would be nice, but you'll have to keep the stock bearing cups due to the Raleigh threading. Sugino Maxi 3-pin would be a proper period replacement, anything higher class would start overdoing the frame. I believe they already came with Weinmann center-pulls, so you're good to go there.

And just stick with the 5-speed cluster. Anything more means you start having to worry about spreading the rear stays, just to pick up one (or maybe two) extra gear choices. Likewise, just stay with friction shifting, and keep it on the downtube. It works better that way.