Tamron SP 54B 300mm F:5.6

I am trying to engage an old telephoto 300mm Tamron SP lens into my Canon EOS 450d (Canon Digital Rebel XSi), but I haven’t been able to find any adapter in the market. The exact model of my lens is “Tamron SP 54B 300mm F:5.6”. Respecting the mount, I have an ancient adapter for my old analog reflex Praktica. The lens has a bayonet mount, and the adapter translates it into a screw-threaded mount. In both bayonet and screw mounts there is a brand name: “Adaptall 2”.

Someone has told me to buy a “M42 to EOS adapter”, but I am not sure if engaging two adapters in serial, would let me focus infinity afterward.

So, I am looking for an adapter that let me match correctly this telephoto lens to my Canon EOS 450d. Here is a picture showing the mount and the old adapter. Any hint would help me for sure.