Welcome friend. I didn’t wrestle in college, but I wrestled through high school as a small heavyweight (230-235) as a sophomore/junior and then as a big cut-down-to-215 as a senior. I understand (perhaps better than some of the others here) why the coach might think your style is better suited to heavyweight, and there have been a number of successful heavies recently that were in the 220-230 ranges, so I get it if you’re on board.
As noted above, you’re not going to put on 20 pounds of “dry muscle” but I certainly expect that you can come back at 230ish and in good shape. It’s debatable whether there’s a benefit to being 220 and still shredded vs. 230 and starting to get a little blurry; my thinking would be that you should train as hard as you can while eating as much clean food as you can, and don’t worry too much about whether the number on the scale lands at 224 versus 231.
Having wrestled as a smallish heavyweight, though, I’d lean towards “get as big as you can without feeling like you’re getting sloppy” - don’t worry about keeping veins-in-your-abs leanness, as long as you’re not getting outright fat. I was a pretty decent 215-pounder as a senior (32 wins, sectional champion, state qualifier) and when I had to bump up to heavyweight for a dual match here and there, I really noticed the missing mass (i.e. even some mediocre heavyweights, I’d beat like 12-1 instead of scoring a fall because I just didn’t have the “mass” to score the fall).