Congrats, on finding what is also my dream car! I love the Cleveland, factory 11:1 compression was just insane. I used to have one that I was going to put in a project but had to give it up due to financial pressure, but I did an absolutely autistic level of research into the Cleveland's so I can confidently offer some advice.

1 problem with them is oiling. They have a "simplified" top end oiling system vs other engines, net result of this is the cam and top end get way more oil than they need while main bearings 2-5 (oiling goes through main #1 on its way to the cam so it's usually fine) get starved, leading the the C and M engines well deserved reputation for fast wearing bearings. Absolute best fix is to sleeve the lifter bores, giving each only a 1/16 feed hole. This keeps pressure in the bottom of the oil system instead of all the oil getting dumped into the top end. You can also put restrictors in the passages between the cam and main bearings, but that's more a bandaid fix than a real solution, but if your budget is tight it's an option.

As far as performance mods, you can't go wrong with an aluminum intake to cut weight if nothing else. For exhaust, Tri-Y headers sound absolutely amazing on Cleveland's, buy all the ones I've seen are quite pricy. Cleveland's also share dimensionally identical lifters to Windsor engines, so If you do the lifter bore sleeves you can just use much cheaper and more available Windsor lifters to do a roller conversion. You can find Cleveland specific roller conversion cams pretty easily too (I know comp cams makes a few).

Just be aware you cant use Windsor lifters without doing the sleeves since Cleveland lifters have extra restrictors in them to try and alleviate the afformemtioned top end oil flooding issues. If you put Windsor lifters in a Cleveland without the sleeves it'll apparently pump the entire contents of you oil pan into the valve covers.

If you want more info/advice I highly recommend checking out the tech articles on the Pantera forum, those guys have spent the time and money in real racing environments to learn all the real tips and tricks for these engines and are not shy about sharing it.