I have a 900 but if you do a search on this very subject you will see the same response on 1500, 1600, 2000's I assume 1700's, Classics, Customs, LT's Meenies and Voyagers. I've read these pages for the better part of two years, it's a good source.
Fact is, I wish two stickys were at the top. Yes, the harbor freight and it's clones are good jacks to go and YES THEY ALL PUT OIL IN THE AIR FILTER.
Think we've had 3 of those threads just this week.
2x4's if they fit under (need 1x4's for the 900 it's too low). The hockey pucks too. But if you haven't had time see if you can't get on the lift. Some will fit the 1600 width but others you will have to add the wood to get across the frame. If you have to balance on the pan, don't worry bout it. Long time but last I knew missing member Rich Locklear used to say how he had his 1500 up on the jack balanced on the oil pan and frame most of a winter or something like that. It's cast not a thin pan.