Hi Ray, The Insurance on mine is lumped in with my DD & homeowners package discount with Travelers. I think it raised my car ins. prem. about 1K. The policy is an agreed value type on fire, theft & vandalism with a 1K ded. on collision. I was told that it didn't qualify for "classic", "collector" &/or "antique" type ploicies. That may not be true as I really didn't think the price thru Travelers' was excessive for where I live, NY/metro/suburbs. Look around though. For me it was price vs. lack of having to do any research right away plus I have no milage/use restrictions.
Modified vs stock is tough to answer & it is more personal. I'll offer this thought to you. Box Stock: These cars were big $$$ new so most orig. owners probably were like the guy I bought mine from: well healed, paid cash for the toy, went back to dealer for service except oil changes. Therefore now the guy is my age, 53, & doesn't use it enough to keep it because it just sits in the garage. Money not the problem, just a change of mind-set or scared of parts being NLA & doesn't want to be a shade tree mechanic because he's too busy making $ in his own business. So sell the car & find another hobby. Or they sell because the value increase didn't materialize like everyone thought. Either way the car was book maintained...not perfect but better than nothing.
Modified cars: way enthusiastic orig. owner or the second owner. Either way these guys are real "car guys" and you know that means anally retentive maintenence! Yes the car is driven hard...but how do you drive an F1 motor hard?? As a rookie I'm learning that the few judicious floggings I do to mine the more it says..."bring it, dude!"...and the smoother it runs. Oh, the mods for these cars are not cheap! So who is going to neglect that kind of investment??? Just go to Haibeck's site & see how much $$$ it costs to get some real HP gains over stock. These cars are not like a regular sb chevy...change the cam & heads & intake & away you go!
Bottom line, due your research on a particular car...ask here & probably someone knows the car if it has been modified. Why? There aren't many places that do that stuff to ZR-1's so it's a small community & you will get the dope if it is out there.
Sometimes I wish I had bought a modded car, would have been less $$ than my box stock, one owner... 400 rwhp from Haibeck costs about $10,000.00...see what I mean? Would you abuse that?!?
Again, sorry to be soooo long about this.
Tom