Hey Lucas,
You could have and still could remove the block from car in the time that you say that you've spent on this job of rust removal...so far. And, you say not done yet..bummer !
I'm going to tell you what I just did and you can use info or ignore it,eh
.
I just cleaned a B block and have it into a short block form right now. Another block that I just did rust removal from recently, I put on an engine stand with an ability to turn this block (flathead V12) anyway but loose ! Same for the just done B block. By being able to 'rotisserie' the blocks, when I made some rust removal tools..something like yours, eacn time that I worked rust loose at the BOTTOM of the block, I could then turn block on end and blow and poke loose rust out. It was amazing , the amounts that came out of both blocks. Now the V12 had THREE pan rail plugs,each side, that I popped out. I had to use drills to bore thru the rust , there was that much.
That got me to wondering...if it would be practical to put soft plugs in the new A/B blocks being made...near the bottom of the water jackets
Such plugs would, if practical, make for an easy job of rust cleanout.
After being satisfied that I'd taken out all the rust that was possible with primitive tools, the next step in my process was the most satisfying.
Plug up the water jackets..i.e.- head on top and plate off the inlet hole.
Fill the engine block with EVAP-O-RUST, right out of the containers..no diluting. Leave that stuff in the block for couple/few weeks. Then drain your cleaner back into containers for REUSE..yes reuse ! This stuff is safe and has not harmed my hands/clothing ,etc when it got on me (OK, I'm clumsy ,eh
). And NO neutralizer after use either !! WOW ! What rust was left (on walls) was converted and it converted any loose stuff so that it was dark colored mixed in solution.
I am very satisfied that I've done a better derusting job on these too blocks than any other in the past. This stuff does NOT attack good metal...only rust. I use the new style anti-freeze thereafter to keep block clean.
BTW...I guess that you can do the same with block in car...just may not be as thorough.