Ok, the date -- and the fixed chokes make more sense.
Value ?? since its an IC / Mod its reasonably desireable even as a fixed choke gun ( for upland birds, some sporting clays ..etc) - but I still think the value is between $ 500 and $750.
To get between $ 700 and $ 750 its going to have to be virtually new../ with no handling marks on the metal or the stock and forend.
$ 600 - $ 700 is probably realistic in very good condition.
$ 500 - $ 600 is a good average price
You did fine...
Here is a photo of my Lightning from 1988 ... you can compare the condition with yours... Mine has screw in chokes / probably 90% with some handling marks ...value ...maybe $ 900 - $ 1,000 ( cost me new, in 1988, about $ 750.) ...but its not for sale ....
View attachment 62350
I have over a dozen Browning O/U's -- all Citori models ...trap guns, skeet, etc ... and I really like these older Lightning models. I pick them up used, when I can, especially if they have some scratches on the stock ( with screw in chokes ) for around $ 500 ....and I refinish them / put them away for one of the grandkids ( I have 10 of them now..) / maybe a 16th birthday or something ...so I have 3 of them put away now / including my own that I don't shoot anymore.../ same thing with Browning BPS pumps ---if I find a clean one that just needs a little TLC ....(if they have screw in chokes)..and I have 2 or 3 of those too ... ( stuff keeps following me home )
But I pass on any Browning, as much as I love their guns, without screw in chokes ... just not versatile enough to suit me ...even as a gift to one of the kids - and that's what hurts the value on your gun. Now you can add screw in chokes / Briley will do them for around $ 350 ....but it isn't really worth it / unless you're going to keep it forever. In your case / I think you made a fair deal - shoot it as is / and enjoy it / don't worry about what its worth except for insurance purposes...
Anyway - that's my perspective. Take care / and go have some fun with the new gun ...