Lens mount adapters for Komura 135mm f2.3 preset

Hi all,
I recently ran across a Komura preset 135mm f2.3 lens. It currently has an M42 mount attached, but I'd like to switch it to either a Leica M mount or a Nikon F mount. The M42 is attached with 3 set-screws and would be very easy to change if I could find the proper adapter. I am not interested in using a Nikon to M42 adapter, because I either lose infinity focus or have to add elements to the formula, neither of which seems a good option. I have grave misgivings about the quality of glass in the M42 adapters. Any ideas?

It sounds like it may be a simple T-mount lens, whereby you loosen the three screws and unscrew the adapter, then get whatever T-mount adapter you want and screw it onto the lens and tighten the three set screws. Certainly T-mounts are a dime a dozen for a Nikon mount, but I'm not sure about the Leica M. And I'm not sure what good it would do you on the Leica, in any case, as you couldn't focusing it using the Leica rangefinder and as it's a telephoto you'd have limited depth of field on your guesstimate focusing.

If it's a T mount, it should just unscrew. Grab the end and twist anti-clockwise.
You will have to guesstimate focus on a Leica IF you can even find a mount.
And that begs the question----WHY?

If it's a T mount it won't work on your M. Besides, who would put a Komura lens on a Leica?

Thanks for the replies.
1. It's not a T-mount. I tried that. The rear adapter flange is quite a bit larger than a t-mount, and it's not threaded. I suspect these weren't designed to be user-changeable, but it's such a simple design, anybody with a screwdriver could do it -- provided they have the proper adapter to swap out.
2. You're right, I wouldn't be able to focus on an M3. I really hadn't thought that out. I'd mainly like to use it on my Nikons, because it would be fun and I think I can count 17 aperture blades! Now that could make for some cool bokeh. I just like to tinker. BTW there are a few Komura lenses on eBay selling for $1000+. I know, you can't believe everything you see on eBay, but I thought where there was smoke there might be fire. Old Komuras seem to have a decent reputation, so I thought I might have found a sleeper.
3. I can't afford Leica glass. I can't even afford Voigtlander glass. We're going to have to eat franks and beans if we want to pay the mortgage this month. I've got my head above water, but just. So I found a dusty old lens for a few bucks and thought I might give it a shot.

Can you post a picture of what the rear of the lens looks like -- maybe a couple of views?

Three views of the lens mount

Here are three views of the lens mount, from left to right: 1. The adapter itself. 2. The lens rear without the adapter. 3. Side view of the lens with adapter removed. The rear of the lens is 55mm in diameter without the lens adapter. It was a 'pentax screw' or M42 mount attached, but I'd like to use it on a Nikon F. This is NOT a T-mount. The adapter doesn't screw on, it slides on and is held in place with three broad, pointed screws that fit into the v-shaped groove on the back of the lens. I don't know if these were intended to be user-changeable, but all it takes is a screwdriver (and the replacement adapter, which I lack). Thanks for any help you can provide.