I will give you my thoughts along with what I feel are the pros and cons on chassis paint options.
POR 15 - I have not used this product so I’m not speaking from experience, just what I have seen written about the product. This is an excellent product if you are looking for protection from corrosion, chips, and or scratches. It can be applied with a paint brush and still come out with a nice looking job and it could be applied without having to strip everything off the chassis. If you are looking for something you can paint on the chassis and never have to worry about rust or chips from flying rocks, this would be high on my list. If you are looking to build a “show” truck this may not be my first choice.
Powder coating – This process will give you, in my opinion, the best looking results. The Chevelle SS on the site that you posted looks to me like the chassis has been powder coated. You will have to strip everything off the chassis and take it to someone who has the equipment to media blast it and do the powder coating. I don’t think it you will get as much protection as POR 15 will give you, but is probably the next best product. This would be my pick if I were building a show truck.
Epoxy primer – If you are not going to use POR 15 or have the chassis powder coated, I highly recommend using an epoxy primer that is for direct metal. This is very good stuff and is engineered to bond to bare metal. This is a two part system, you must add a hardener to the primer and you only have a short time to work with it before it begins to set. Along with cleaning up all the rust you will need to get ALL of the oil and grease off of the surfaces or you will have problems. Once you get the epoxy primer on you can put pretty much anything you want over it.
Base coat/clear coat – This will look very good if applied properly, especially if you want a very high gloss finish. This is not something I would recommend for a first timer, you need at least a little painting experience to apply this properly. You must use epoxy primer under this system.
Rustoleum – This is a good, inexpensive product. I have used it on trailers, grills, lawnmowers, all kinds of stuff, easy to apply and holds up well. However, if you are planning to remove the cab, bed, engine, transmission, etc. in order to paint the chassis, that’s a lot of work. I would be looking at something of a higher quality for the job. If you are looking for something that you can crawl under the truck and dab on with a brush to cover up a few rust spots, this will work well.
Hope this clears up some of your confusion.
On the 69 Chevelle SS, if that guy does the rest of the restoration with as much attention to detail as he did the chassis, it will be an awesome, awesome car.
Don