I normally don't like to work with blocks that have split pan rails - this is usually due to a freeze situation (no freeze plugs on these blocks). It would not hurt to have that welder check it out - at least the pictures and get his opinion on that type of repair, associated costs, etc.. At least you'd have something to go on - in making your decision. Best of luck! B&S
You can also use an 8BA block as well. Most all the 59 stuff fits Heads cam etc. Except the pan.fuel pump, pan. You have allot of options.