+1 on Howard's retro-fit roller stuff.

I used their cam and lifters (very mild specs) in a low mileage SBC crate motor just to get rid of the flat tappets. They had the cheapest "name brand" parts and they have worked great for 5 years.

Howard's retro fit cams can use the stock distributor gear also. Other brands can too, but you need to ask before you buy. Some require bronze or other types of distributor gear to prevent cam failure.

Keep in mind that you will also need some way to control cam end play when switching to a roller since there is no rearward thrust from the lifters to keep the cam from walking forward. This can be as cheap as a simple cam button or as expensive as a new timing cover with a roller bearing. End play needs to be set, too. You can't just drop in a button and call it good. If you just run a simple button, you probably should upgrade to heavy duty timing cover to prevent flexing.

Considering the global trade mentality that prevails now, there are a lot of name brand parts that come from China or India (or worse), but most of the big companies hold them to a higher standard of quality control. That makes a huge difference.

Those EBAY lifters are could very well be rejects from a run for an American company that they are trying to dump for a little profit. In the case of lifters, all it takes is one lifter to fail out of sixteen to leave you with a pile of junk. Not worth the risk, IMO.