This is what I would do. With all the unpredictable delays I encounter these days, I no longer book short connections unless there is no other choice. It's also very difficult to estimate how long immigration and baggage claim will take.

Rather, I do as mhnadel suggests and book a comfortable connection (at LAX, I'd say about 2 hours is comfortable enough). When I get to the UA terminal, I simply ask to standby for the next available flight. I can't remember the last time I haven't cleared onto an earlier flight than the one I booked. (But then I am always going to SFO/SJC, and there are flights every hour, half of which are delayed or cancelled, so I never know in advance which one I will be able to make.)

I would book the later connection, and hope I get lucky. Having a guaranteed seat on the later flight and standing by for the earlier one is a better situation than the reverse.