Old rims tubeless

I do. But then  I use any old rim. Don't mess about with expensive kits. Get a roll of Tesa tape from Ebay and some cheap .Chinese valves. I defy anyone to tell the difference .

If they don't seal before sealant goes in, even just for a few minutes then stick another layer of tape in. I have done quite old rims, not nearly new like yours. 1988 Mavic off my first MTB worked fine.

Depends if you're using tubeless ready tires

I've done plenty of tubeless installs on non tubeless rims. Some were fine with Tessa tape (dtswiss), others needed to be ghetto as the tyre would drop straight off the bead at low pressure and needed the extra friction/size buildup of the tube.

You'll be wrapping numerous layers of Tessa if you're trying to take out as much slack as a tube will make up.

Single loop conversion kits with a shoulder would be my preference on a sloppy tire/rim combo. This was how DT originally entered the tubeless game.

I use ghetto tubeless with a split inner tube and art latex as sealant.

Get a tube that's a couple of inches too small for your wheel (so a 26" tube for a 29" wheel, a 24" tube for a 26" or 27.5" wheel). Inflate it slightly and put it onto the wheel (so that you can get the seams straight) then use a sharp pair of scissors to slice it open along the seam. Now you'll have a flat strip with the loose edges hanging over the sides of your rim. Clean all the talc out of it (a wet rag with dish detergent will work fine) then fit the tyre over this (so the flaps of the tube are hanging outside the tyre. Add 100 ml of sealant (I use 50% liquid latex, 50% water) and then inflate with a pump. I pop down to the gas station and use their pump. Just inflate it enough that it will hold air and check that the beads are properly aligned. Spin the wheel to distribute the sealant. Fit it to your bike (for safety if the tyre blows off the rim - you should always do this when fitting any new tyre) and then inflate to 30 psi and take for a ride around the block to bed it all in and get the sealant worked between the bead and rim strip. Leave it overnight for the sealant to seal up any leaks. Once it stays inflated overnight, use a sharp knife to trip the flap of tube hanging out the side of the bead on each side.

I started doing this back before proper tubeless tyres. You can usually get non-tubeless tyres to work, but it's hit and miss, often the sidewalls are too porous. Proper tubeless tyres make it realy simple.

Need to keep pressures up as narrow wheels will roll the tyre so it burps if pressures are too low

Particularly as the bead shelf rends to be short and rounded, so doesn’t take much to dislodge the bead. Tubeless ready rims have long flat (sometimes hooked) supportive bead shelves specifically to avoid this.

Need to keep pressures up as narrow wheels will roll the tyre so it burps if pressures are too low

A split tube ghetto setup cam help that a bit vs tape.  There's so much friction in the system from the rubber on rubber interface it will tolerate a fair amount of mistreatment.

If it's a non tubeless ready tyre painting the inside with sealant (you'll probably bin the brush after) can help.

Ghetto tubeless was the way to go before rim & tyre manufactures made it easy for us.

I have used this method, with an inner tube

& this method with gorilla tape

Both methods worked well

I used stans rim convertors, they have a sort of bead lock molded into the edge of them.

Have gone back as far as original mavic 117 and 217 (which are both mid 90s).

Also, using the stans strip means that i don't need to use tubeless, or even tubeless ready tyres.

I did some original Green Michelin Wildgrippers tubeless on 217 for one build and also the original smallblock 8s in their lightest guise plus some conti speed king supersonics...

Oh, have also done mavic open 4 road rims tubeless with various cx tyres, it works, but wasn't really worth the effort over using latex or lightweight tubes.

I pop down to the gas station and use their pump.

I guess air is a gas