No. You will surely be disappointed. The last GK found on the image of the squad list that I have posted was bought from the scouts' list (23 years old, close to 7 stars, one-on-one stopper special ability). He was very poor relative to his quality; lots of ratings of 6. He even passed back to the ball to an opposing attacker once in a Cup match and the attacker scored. Hahahaha. My team got knocked out of the Cup partly because of him and also lost the a C.L final partly because of him. It was as if he was completely absent in some matches.
Here is an image of most of the ratings for the C.L final. As you can see he got a 6, and he conceded the only goal of the match. Going by the ratings, the defenders did their job, but not the GK.
In the next season, I bought another GK, but this time from the auction market.
This one was better than the one mentioned earlier. He was more present in matches.
Given that you have a decent amount of tokens, buy a few 5 star, 'old' (26-28 years old) GKs from the market (say 3, unless your squad has already more than 19 players), and try them one by one for say 3-5 matches each (you can test them in friendly matches too, but the opponent has to have some good attackers to test the GK). You will more likely be able to get a good one this way. Then, discard the bad one(s), but keep the second best as reserve. And no need to train the GKs for the special abilities. If he came with one, it is a bonus, but if he did not came with one, then no need to add one. If the GK is good ('internally'), he will perform well, even without any special ability.