I'd like to hear good and bad stories on flathead lifters. I know there are some horror stories out there on Johnson style copies. There are several reputable companies that market Johnson style adjustables. I've also thought about going the original lifter route and just chucking the valves up in my lathe for fitting as I go. This is going to be on a mild street 258" 8ba.
If you use the Ford factory method of adjusting the valves, make sure the seats are ground at least to max width. Old timers used exhaust valves in all 16 holes. The last 3 of these engines I've had a hand in, the adjustable lifters were found on the interweb from a Ford tractor parts company for quite a bit less than the hot rod companies. If you use adjustables, remember to drill the block for a punch so you have a positive hold when setting them. The ''Johnson'' wrenches are useless.
While not "Johnson", TRW, in the Industrial/Commercial line, used to sell adjustable lifters that worked fine, especially for a street driven 'cruiser', although the engine that I had them in regularly turned up to 6K rpm, & I never had any problems with them. It had a Howards Cams recground cam & Isky valve springs. They were a lot cheaper than what was offered by the hotrod vendors!
No problem with the speedway one for me and as 302gmc stated drill the holes cause the "wrenches" suck
Go with the adjustable lifters. They work well and make it much easier to adjust the valves. I prefer the type with the open windows. They work better than the solid type which don't easily catch the pin inserted in the lifter bore holes you hopefully drilled to keep the lifters from spinning while you adjust each valve. If you find a set of old original Johnson's have them reground and hardened. With the flathead's relatively low valve spring pressure they will last a long time.