WAM rebuilt a 390 for my 1970 F250. I started driving it in late October 2016. The engine lost compression in the sixth cylinder in May 2018. I drove it about 5,000 miles during that time. It also has water in the oil.
When I called them about it they said that the one year warranty is expired. They would not fix it.
My mechanic was working on another car who's engine was rebuilt by WAM. That engine also needed to be redone. I have a new mechanic and he has had bad experiences with WAM and so has the guy who rebuilds engines for him.
My old mechanic has used WAM many times and says that they used to be good, but now some employees have changed and their work is no good any more. My new mechanic would not use them either.