Here's the rundown --
First thing to check is, do you have an 8-9-10spd freehub.
If not, the easiest way to get to 1x is to buy a wide-range Sunrace 7spd cassette and a cheap narrow wide chainring off Amazon or Ali. A lot of vintage derailleurs will work with that; Shimano tends to punch above its class, and some of those old Suntour derailleurs had very impressive capacity for their day. Only problem is, you're very limited in gear range. Fine for a townie, but if you want or need range, you need an actual wide-range cassette and that pretty much starts with 8 speed.
There are ways of cramming an 8, 9, or 10spd cassette onto a 7spd hub; I've done a couple of builds where I deleted one of the middle cogs from a Bolany 9 speed cassette; it works OK I guess with a 9 speed shifter or a friction shifter. 8 speed spacing is the same as 7 speed, so theoretically you could just delete a cog and go. Easy enough if the cassette comes apart, or you may be able to delete the top two and re-use your 7spd 1st position cog. I've also read you can delete a cog from a 10 speed cassette although I've never tried it, and am not eager to. To be very brief about it, this is one of those hacks that sounds easier than it actually is.
To me it makes more sense to do a freehub transplant. You can't do that with every hub but I've only been skunked once with Shimano (a "silent drive" hub ... haven't tried it with MT60 although I'm sure somebody here has). An 8-9-10spd freehub can be bought new for about $20; the swap itself adds negligible time if you're overhauling your hubs anyway. You do have to fiddle with it (move spacers around, re-dish the wheel) but it's not terribly difficult.
Having done that, if you just want to make the bike go, I can't say enough about the M5120 rear derailleur. Paired with a wide range Shimano 10spd cassette, I don't see how you beat it at any price. Wifey is running one paired with an el cheapo Deore shifter on her mountain bike and I'll be danged if it doesn't shift almost as good as my 10spd XT rd paired with a Saint shifter (almost .... the derailleur is pretty much invisible but I sure do love that Saint shifter, well worth the buy imo if you can find a good price). Right this minute, I think that's the best 1x solution if you want to actually ride the thing. The Advent 9 and 10 speed 1x systems also work well enough (wifey is running their 1x9 on her gravel bike, I'm not a fan but she likes it). Haven't done a build with Cues yet. The SRAM options get terrible reviews so I don't even plan to go there
If you want to maintain a vintage look, and still have range, look up the "roadlink," which allows vintage shimano mtb deraillers to gobble up a wide range cassette. Certain ebay vendors will send you one for free with the cassette. I briefly ran an old 500LX derailleur that way, set up with a friction shifter and it worked OK I guess.
If you want to use a vintage chainring, buy the pair ... you may be able to use the front derailleur as a fixed chain retention device, just depends on if your low limit screw has enough range to fix it in the right place.
Although if you're going to all that trouble, why not just wire it up? I can see the logic in ditching the big ring in favor of a chain guard, for me the big ring is just for decoration anyway .... but why delete the granny ring if you don't have to? And if you have a granny ring, you don't need more than 30t in the back; and if you don't need that, you don't have to upgrade your freehub.... cue Dr. Evil, "Aw what's the fun of that?"
But, you had one simple request (sharks, with frickin laser beams attached to their heads) so there you go. I will say, if you're gonna do the mad scientist thing, consider investing in a some decent thumbies that'll run in friction mode. Nicer feel than clicky shifters, more reliable, less time spent fiddling and cursing, works every time by definition. I'm always on the lookout for a good price on old Suntour power ratchet thumbies. Or look at the Rivendell Silver shifters, or the Diacome ENE shifters -- modern versions of pretty much the best shifter ever made, if you ask me. Any of those are well worth the investment if you plan on spending time down in the lab with that bike.