Bummer, Greg!
The 7 leaf springs are the HD springs, as in stouter than the 9 leafs. At least this is true with the factory/original springs. Aftermarket stuff may be different. Check with your supplier for that info.

If you are not trying to keep the car "original", by all means replace the rear cover with the stouter, thicker replacement cover. If you plan on having the car judged(NCRS/Bloomington), the aftermarket cover will result in a minor deduction.

Replacing the entire fuel line with the body on the chassis is next to impossible, if you do it the way it is from the factory. If you just want to cut/splice(with compression unions) the lines, you can do it that way.

I am not worried about NCRS competition. I would go with the heavy duty differential cover. Where the fuel leak is at, it would be next to impossible to just splice a piece in there. It is where it goes into the frame in front of the rear tire. I think it would be better to replace the whole line. I don't know what the rest of it looks like and I don't want to go through splicing in another piece a year from now.  I don't have the containers to put 3/4 tank of gas in or a pump to put the differential grease back in. This is a good time to replace all the worn out and dried bushings in the rear end.

The spring is from Mid-America Motorworks if that make a difference.

 

Ya...the line going into the frame is what makes it impossible to do with the body on.
You can route it differently, and a lot of people do it like that. As long as it is protected from debris(rocks, curbs, exhaust, etc.), you should be otay.
I would check the specs on the part # for the spring, or call Mid-Am, just to have the info on what you got.

If your concerned about the spring call Mid Ameraica and explain your plight I'm sure that they will be happy to work out and exchange since it sounds as though they will bee Seeing you an George ($$$) again in the very near future.

As for the gas line I used to build tall 4wd trucks. These things are notorius for haveing both gas & Brake lines replaced in non original means due to the changing of both suspension, body, and the ever presence of foreign debrie. One trick we used to do is run them inside a vinyl nylon braided hose and mount them as high up in the inner frame as possible. This way they were outta harms way and protected as well.

the fuel line is going to be a pain..  you will need to lift the passenger side of the body off the frame to do this..

just unbolt all 8 body mounts and lift the passenger side up about 3 inches..  there still is not alot of room...  but it can be done..

I just had the car looked at who has worked on Corvettes before and he daid about 3-4 hours of labor to get it all done. He won't ne anle to get to it for about a week though because of all the he has backed up. He does this on his free time and is a mechanic at the local Ford dealer so he has all lthe right tools to get this done as well as that all important lift. It looks like next year I am getting that 4 point lift I have been wanting.

 

FOR SHAME!!!!
A FERD guy werkin on yer 'VETTE?!?!?

This is the non Ford product in my garage. I have 2 66 Thunderbirds sitting right next to it and a boat on the other side. I also have 2 05 Mustang GTs, 03 Expedition and 03 F-250. Maybe all these Fords jinx the Chevy.