I don't know those particular lenses though no doubt someone will, but I'd say they will be fine. I haven't used a wide field Ektar but I do have a 207 Ektar which is a superb lens. About the only thing you really improve on with newer lenses over the best quality older ones is the coatings, and that will really matter only with backlighting or strong light sources inside or close outside (or relatively close, depending on the coverage of the lens) and even then it's mainly a loss of contrast so in black and white you just print it on harder paper. More modern shutters are also more reliable, less likely to need work and easier to have serviced but if the older ones (like on my 203 Ektar) are working ok they're fine.
16x20 is loafing for 4x5. That's only a 4x enlargement. The equivalent in 35mm would be a 4x6 print. Either of the lenses should resolve more detail than you'd ever see in a 4x enlargement.
It took me a second to realize how small 16x20 is for 4x5. I could probably shoot through a coke bottle and it would be tack sharp. I doubt I'll ever go higher than 16x20, but it's nice to know that I can!
That's a good point about coatings - flare is the most obvious thing I've noticed when using old lenses on smaller formats.
After thinking long and hard about it, I decided not to take the deal. I'm in a one bedroom apartment and I just don't have the space for 4 x 5 darkroom. Maybe in the future I'll be able to do it, but I don't want the stuff to just sit in the garage for five years while it waits for me to get a larger place. I try to live within my means and part of that is not getting stuff that I can't use. Thanks everyone for the input! I really appreciate it
Roger makes a point about coatings, however I've been using some older coated lenses in Turkey and what's noticeable is that I've had no flare with a 1950's CZJ T coated 150mm Tesssar and a late 60's 90mm Angulon, also a 75mm Super Angulon when the multi coated lenses on my Canon EOS have been unusable alongside them. (This is on quite a few ocassions).
Some lenses are better coated than others and coatings evolved, so a late version of the 203mm f7.7 Ektar that Roger refers too is much better coated than the earlier ones (at least with the UK made versions). My coated Tessar is very heavily coated but because of this has a distinct blue tinge, it would need heavy correction for Colour work.
Those Canon multicoated EOS lenses also have far more air to glass surfaces than the simpler LF lenses. The more air to glasses surfaces the more important coatings become and the more difference you will notice between quality of coatings.
I checked the serial number on my 203 Ektar once. That was back when I first got it in the 90s so memory may fail me but I seem to recall it was made in 1947. I've noticed no flare problems from it.