What wouldn't be an insulting offer?

I found 2 BB with 727s for sale today. Listed for $750 and $700 OBO.

Obviously, if it's OBO, he has room to haggle.

The first one (the one I would prefer) is a '66 440/727 with 67k Orgi. miles
- $750
- Missing Valve Body
- Missing Trans Pan
- Complete with accessories, can hear run

How much would it cost to replace the valve body and trans pan? Priced them at JEGs for about $200-ish for the two

The second one (better deal?) is a '75 440/727 with 35k orig.
- $700
- One owner
- Complete top to bottom
- Can hear run/ move


So here is where I am at, I want the '67 because aren't they higher compression? (10:1)? but is the extra miles / missing pieces worth it? The second one, I would just replace seals and check the valves, don't think I'd have to rebuild from the ground up.

I asked the guy if he would be interested in trades + cash on top, but if not, what would not be an insulting offer to shoot him? I've seen 440/727s go for well over $1000 still in RVs and such. These are pulled and from the ad, sound pretty good. Would have to check.

For trade I have a BMW shell and my slant 6, but could always run them to scrap to get him actual cash if he wanted that.