I started to take apart one of my spare motors to start building it, I wanted to ask the pros about these weld spots on the crank. I am assuming this is heavy metal for balancing and I dont think it is factory, the crank is standardsize right now and has a name "phillips" painted on it as well as a matching name on the balancer. I assume a shop did this to keep the parts together.
Also all the rods except one has material ground off the lower lugs, I assue the one rod untouched was the lightest and they ground the rest to match weights.
My question is can I assume this crank and rods were balanced, and should I reuse the same damper that apparently was used or matched to it, It looks like a regular damper except that there is a ledge around the circumference where the timing marks would be.
I dont have the flywheel for this motor, can I just get a new flywheel and balancer without upsetting any previous assumed balance job?

here is a picture

Most likely the assembly was balanced to use the standard external balance Ford hardware for the 351C (28oz) so by using a standard weight flexplate or flywheel you'll keep the balance reasonably good. With that said what probably happened was they had to add a bit of weight to the crank to match the bob weight and they just welded up a couple of the factory balance holes. This is perfectly fine to do and it will cause no problems.

The only problem you can run into with some balance jobs on externally balanced engines is when the person doing the balancing does something weird with either the balancer or flexplate/flywheel. I always leave that stuff alone on a job like this but many people don't. I had a 302 based 355 inch circle track engine that came through the shop last year(used a turned down 351 C crank. I freshened it up for the customer and then he wanted me to run it on the dyno. The problem was that he didn't know which of his flexplates were to be used with the engine. It turned out to be a "custom" one complete with extra holes and more weight welded on.... I found this out after starting the engine with a standard 28oz and having it vibrate. We were fortunate that he still had the flex plate that they had used with a small diameter clutch on the race car otherwise I would have had to take the engine apart and rebalance the assembly.