I am slotted for reclass school in the Army reserve, but the VA just put me at 70% service connected. Can I still reclass? What can I expect?

The VA rating percentage has nothing to do with your Army Reserve, other than completing VA Form 21-8951 annually. Many elect to waive the 63 drill days worth of VA compensation and take the drill pay.
You have no profile, and I wouldn't volunteer to seek one. Of course, if you believe any of those conditions interfere with your ability to complete your duties, you should research your options before raising the issue with anyone.

I think that would be tricky, based on my previous experience.

For some conditions a letter from a civilian Doctor stating the condition or illness “ is more likely than not a result of “ can serve as a Nexus. Some conditions or illness will not become apparent until years after your service has ended. And even if a claim is denied there are appeal options now available. It may not be easy and the fight long but staying in the fight is the right thing to do for your and your family. I know a lot of younger and still serving vets may not feel veterans organizations worthwhile but really that’s where your going to find your SME’s for all things VA. That and your own hard work and research will win the day every time.

The Army really doesn't care about your VA rating. Your fitness for duty is solely dependent upon your physicals and any boards they may result. If your PULHES is within specs (or the board says retain) you are good to go.

I don't want to make assumptions here on what your disabilities entail, but if you are truthful on a PHA, it is highly likely that you will affect your PULHES which may well disqualify you from some MOSs and potentially send you to a PEB/MEB process.
I would not recommend deception, nor should you try and perform duties that would make your conditions worse.
Be smart. Your health is way more important than any other consideration.

There are a few different ways to handle this situation. The end state is that it does not effect your current service unless as stated below you choose to pursue a profile. To better understand how your benefits work and what you should do with your VA pay, check out this video.

https://www.youtube.com/watch?v=l2b1bwSqhHY&feature=youtu.be