upgrading, need help.

So, my two stroke is old, and died after I spilled making a too sharp turn.
I want to upgrade. Bought a 4 stroke off thatsdax.com The TITAN MAGNUM 4
STROKE ENGINE KIT.

Now I am NOT a mechanic. I'm not totally inept, but not a mechanic either.
I DID ask this guy to be sure to include instructions. I also asked if I need to buy a tool to take the chain apart, and put on the new one. Or if that's really needed. Seems some parts don't need replacing. That rear drive gear for example. Why replace it when the old one seems to be the same size and is in good shape? The chain does show signs of wear, and as long as a new one came with the kit, may as well.

But I got nothing. NO replies, NO instructions of any kind. Just a box of parts. (one of which has quite a bit of surface rust, why a "new" engine would have any is beyond me.)

I'm going to go ahead and start taking parts off my bike. What I can at least. I need to know first about the drive chain. Does that need to be cut to be removed? What tool do I need to find to replace that master link?

Then if anyone has a manual of any kind, be it a good video or pdf or something, please post it. I'm not even sure where to begin.
Even a good post saying do this… then… then… would be most helpful.

Yea, been. Posted this on two motorized bike forums at the same time.
The other one actually shot me three videos. One I found on my own but the other two I hadn't, and were most helpful.

Thanks anyway.