UA would not be able to check your luggage through to LH on this itin. The MCT for these two flights is 1:15 and no reservation would legally book you on this itin. If you book them independently, the UA computer will not be able to issue the bag tag with the downline LH flight. New MCT warnings come up in the system to protect against this.

Even if you do not check bags, a LH boarding pass would not come out automatically since your itins are seperate. If a UA rep tries to force the through check in, you might be successful, but if not, as mentioned above, you will be past LH's cutoff time for check in by the time you get to them. The kicker: you would be responsible for any rebooking/accomodations for missing this flight because it is not a legal connection and neither carrier is responsible for you. A restricted ticket could end up down the tubes if you risk it.

Then again, the PS flight could blow in to JFK an hour early and it would all be worth it having that nice seat for a few hours!