OP are you sure you aren't mixing up the brands this frankensaw is made up from? I know I was once toying with the idea of converting a Partner K1250 into a Husqvarna 3120 XP. I posted a thread on here years ago asking for opinions, but it never got much interest and I ended up just fixing it back up as a rail saw and selling it.
As far as I remember the few comments I did get were to poo-poo it and say it couldn't be done, by the usual naysayers, but I'm not convinced. I studied the IPLs for both at the time and I'm sure it was possible just by adding/changing the right parts. It had to be an old Partner, before they changed them to Husky orange version and older still. If you see a real old one they have a cap in the front tank which is totally unused on the concrete saw, but was still threaded to take a screw cap.
I would have loved to have done it and tossed out a few 'I told you so's' but I figured the time it would take me to source the necessary parts, as much second hand as possible, might take forever. Added to that, I would eventually need to sell it on and I considered that trying to ebay a chimera of the most powerful chainsaw Husqvarna make would probably be appealing only to a very niche market of brave souls, regardless of how correct the theory might be.
I might still have a picture of it somewhere, as a concrete saw, but it probably shows what I mean about the oil tank.