First of all it is great that you have a solid background in wrestling! I would definitely look into taking some BJJ classes. That is pretty much a must have now. Not that you need to be a blackbelt, but you pretty much have to know what is happening on the ground since most other fighters do now. Just make sure that you remain proficient in wrestling as well!
Also Muay Thai is an excellent standup technique. All standup techniques can be devestating if they are learned properly so that is really about what suits you more. But Muay Thai is a very dangerous technique that would be a great asset! You could also do something like kick boxing or just traditional boxing if you want. It is up to you, just stick with whatever you choose.
Also a lot of places offer MMA classes that are very helpful. They combine various striking and grappling techniques in their trainings. It is a good class in my opinion.
Hopefully this helpes a bit. Have fun and train hard!