1500+ hours, that just makes my head spin!!! I'll say it again, Im looking forward to seeing this one. Should be a beauty. I have googled the H-61 but keep turning up the same pics. I have scratchbuilt a cab from pics I have found,its posted here somewhere, but am trying to find pics of the chassis and rear of cab. There is a short video of one on you tube which helps a little. I e-mailed the Mack museum a while back to ask for info,but still havent got anything. Maybe they wont send to Australia,I dont know. Might have to go a different direction with it.
Might try ATHS. They have a library and will copy stuff and send it out. Give them an email.
Look around for the library or email them. I know we have a huge library with a ton of research material.