Cannot find the correct brake booster

[Ole Nellie]

I need to replace the brake booster on my 1964 travco but I cannot find anything that looks anything like it it's really big way bigger than anything that I could find on the internet and it has some pipes and hoses and stuff coming out and it's mounted on the frame right in front of the rear axle. I was told that I need to go to Napa to find all of the parts but I just can't find what I need there either.

Also I need a new brake caliper I think it's what it's called it is leaking fluid.

I was thinking of upgrading the brakes to something that is more modern that you would find on a dump truck perhaps but I don't know how possible that is.

Let me know if you think it can be done and also if you got any links of the type of OEM brake booster that will be the same exact as what I have. Everything that I find it just does not look right and it's too tiny looking.

TIA