On balance, one can way the number and degree of flip-flops committed by Donald Trump in his biography against these questionable allegations now being dredged up against Cruz and there is really no equivalence, IOW, Ted Cruz is a liar but Trump has changed his position more often. Gotcha!
That said, your assertion that Cruz is now "solid today" on immigration is unfounded. For the entire campaign cycle, at least after March (wherein, before hand, he supported legalization), Cruz has refused to take legalization off the table, and, at best, says he only "intends" to oppose legalization, which, in legalese, is a "maybe," while e continues to lie to his supporters about ever supporting legalization in the first place.
I have looked at Donald Trump's immigration policy paper and did not see any reference to letting people back into the country, although he has firmly stated that is his position. Of course I did not find any reference to what he would do with those people whom he would let back into the country, would they merely have guestworker status, green cards, or full citizenship with voting rights?
Do you have the answers to these questions?