340 For street duty

If the crank is usable,turn it and run it. .020 under is nothing, and to be rebalanced (piston choice) you will be drilling on itany way. Grind off the welds and have them redone if you have to. If the crank is bad, buy a 360 and go that route with a rebuild. A very mild 408 is much more street friendly and not much shorter life span wise than a 340. And you dont put the numbers matching engine at risk. Not to mention costs. A 340 with a cam and modern parts, with modern machining will make 375hp pretty easy on pump fuel. Just watch static ratio and cam choice for the "pump fuel" part. Get that wrong, and you'll be pinging. A 408 will make 400hp easy, and beyond 480tq..which is really what you want anyway.