Strong suggestion,
The first pic is for a kit or completed chassis that Jegs did as an entry into the Chassis market. It is called a Jegster. Not a good design and will not handle much power. It is ok for bracket cacing, index racing in the slower speeds, Super/Street 10.90 racing. and Super Gas 9.90 racing. For anything quicker it needs lots of diagonal bracing addded.
I am not talking about rules, I am talking about real. That chassis design has too many bars running parelell and few diagonal bars.
The second kit you posted is also good maybe for the same speeds and performance. Neither will handle much power with tires hooked.
What do you have?
What are you trying to do?
What is your total budget for car only with chassis all done?
You can buy both mild steel and chromolly that is already fittedt and welded for not a ton of money. If you can fabricate and can weld there are several kits available that are very good.
Tell us more info?
Ed