Shell Valley has changed owners and the new Shell Valley has a better product.
Do your research.
Go see a SV and sit in it. Ride in it if you can.
Look at others. Ride in as many as you can.
I have worked on SV, Everrett-Morrisons, FFR, Uniques, B&B, Lone Star, Hurricane, Shamrock and installed a 427 into a CSX6000.
All kits have problems. All kits are different. Pick the one that suits you.
The cost to build is the same. Or so close it's not an issue.
Have a plan and stick to it. Don't start out with a junk yard 302 motor budget and 3/4 of the way thru change to a 427 FE. Now you have to change the headers, maybe radiator, ETC. ETC.
My Lone Star had a $20,000 budget. When I got it on the road I had $35,000 in it. And spend $2,000 to $4,000 almost every winter on upgrades.
At the time a Lone Star kit was $6,000 cheaper than the Unique roller I looked at.
It was not to long into the build that I found out the Unique roller was a lot cheaper. To late, had to push forward. More money and an extra year to the build.
Do your research, take your time.
P.S. in today market it is cheaper to buy a completed (used) Cobra and change what you don't like in the winter.
Drive now, work on it when it's snowing.
Dwight