I hope the Swede turns out ot be a very nice rifle, because a nice one of these is one of the best there is. Check it for head space after you get it. Even Swedes sometimes have problems.
I am afraid that the Spanish Mausers converted to 7.62 CETME have a terrible reputation. Many, if not all (?) of these are Mauser 1893 type actions originally made for 7mm Mauser. The old 7mm Mauser was originally loaded to at 42,000 psi. The 308 Win. can be loaded to 55,000 psi, a substantial difference in itself. The Spanish fired a special 7.62 CETME (same size as the 7.62 NATO/308 Win) cartridge in these rifles which took this into consideration.
Unfortunately, this is not the only thing alledged to be wrong with these rifles. At Truco's Masuer forum, there are posts condemning these rifles right now and I have been looking at them. The Spanish made receivers are said to be softer than most and particullary subject to be set back by too heavy a load. Since your rifle could well have already fired a regular 7.62 NATO round, it is imparative to have the headspace checked in these rifles. Alas, this is not good enough by itself. One man claims to have seen chambers so sloppy that rounds could be wiggled in them. Head spacing does not necessarily detect overly big or buldged chambers. Some of the rifles had barrel liners put into them, maybe slopily, and this is another cause for concern.
To top it off, another man gives a discription of one of these Spanish 7.62's going up on him, apparently from excess head space. The gases blew out through the magazine, blowing it appart and taking some nice chunks out of his left hand in the process. That is another problem. If one of these 1893 type Mausers do go bad on you, they will not handle the escaping gases as well as a Model 98 Mauser.
Another man demands that all of these rifles should be taken off the market, because he is convinced that they are all potential disasters waiting to happen. Others say this goes too far.
If you do want to shoot this thing, have the head space and chamber carefully checked. Find out if it has a relined bore. If someone knoledgable like a real gunsmith thinks it is all OK, then shoot it with reduce loads like it was meant to handle. Some say to use loads developed for the 300 Savage, but I cannot vouch for this.
I am sorry to be so down one these Spanish rifles, especially when I am not actually sure of what model you have really ordered, but you should know that they do indeed have a clouded reputation.
As for the adapters, I know nothing of these.