I was a mechanic from '62, until '70. Most of that time (2 years in the Army as a mechanic), I worked in SoCal and the shop had a tow service and a wrecking yard. I had access to all kinds of things. Loved it!
As a life time Ford guy, the FE (wasn't called that, in those days) was MY engine of choice
In '63 I had a '60 Ford with a 300 hp 352 and in '68 I bought a '63 427 LR engine.
I always new about the machined chamber heads and that was one reason that I bought this 361 so, I could work with them. There was probably a transition period in '59 but, all '58 and '59's (332/352 included) engines had them. Most '58's had Welch plug holes (1 1/4) in the heads, front and back.
My block is pretty early but, only has Welch plug holes, in the back of the block, some also had them in the front of the block and you can see the bosses for them on my block.
One last thing about the early blocks, Fords minimum cylinder wall thickness was .170 for a std bore engine. At least from the '58 to the '60 model year, these blocks
were not thin wall castings. Fords first thin wall block, was the 1960 Falcon 144 & 170 6 cyl engines. I've yet to determine when the change over was but, it was somewhere between '60 and '63. I had my engine bored .060 over (4.110) and there is still enough meat to go to at least 4.13. It was common, in the '60's to bore ALL engines 1/8" (FH's up to 1/4") and I didn't know of anyone splitting a cyl wall, not that it wouldn't have happen but, I was a mechanic and a racer and didn't know of any. 283 SBC were done, all the time. A 1/8" over bore on a .170 wall, leaves .108 wall, mostly acceptable today in this world of sonic testers. I even have one and will post my results, on this block.
In the pictures of my heads, I've machined them for 2.09 x 1.656 valves (Stelite Ex seats) and deburred the chambers.