Low compression 1 cyl. late '99 7.3

[Diescipel]

Gentlemen--

New to PSDs but have own my share of diesels, including a factory diesel Toyota Landcruiser, but I need a truck now not a toy. I've been lurking and reading posts and yes I did order a CPS this morning from eBay so I do learn quick.

OK-- there's a truck I'm thinking about. Late 99 F250, 260K miles, 6 spd manual 2000 mi on rebuild, 30k on clutch, clean, fresh paint, has exhaust brake, gooseneck set up, needs tires etc. Price is great, $4500. But the owner reports engine knock, mechanic said due to low compression on 1 cyl. Owner did not have the paperwork from mech., but said he could call him to get actual compression #s on all 8 cyls. (A little fishy that mechanic didn't give him/document compression readings...)

The question is: I am at some point looking at major engine work. What are ballpark figures for

1. Engine rebuild-- independent mechanic & Ford
2. Install used 7.3
3. Install new 7.3 (probably wouldn't bother with it)

In addition, could you answer the following questions:

1. Never had an exhaust brake-- can they lead to engine problems (can't imagine all the truckers being wrong...)?

2. What do you think is the likelihood that this is a ring problem or a valve problem, and so may not require a full rebuild/new engine?

Lastly, I am not a big tow guy or anything. I am just looking for a work truck to do a variety of things (dump runs, haul gravel, lumber etc.) and 4x4 to get away (I miss my 'cruisers!).

Thanks!