Advice for re-soldering 2" copper washer standpipe that barely fits into the pipe in the slab

[Thurmanator]

I recently purchased a house that has 2" copper for the washer standpipe, and the solder joint at the slab was a bit loose. I unsoldered it and was planning to clean it up for a re-solder, but the it seems the pipe in the slab was a bit too small. The copper standpipe barely fits inside the pipe in the slab. It looks like a previous plumber or handyman stretched the pipe just enough to accept the tip of the standpipe.

I'm fairly confident that I can make this work by lightly tapping the pipe with the standpipe inserted to get a tighter fit, but the standpipe only goes in about 1/2" - 5/8". It doesn't appear that the washer drain leaked, so I think it will be fine, but I wanted to ask you guys in case I'm overlooking something. The sharpie line is how far the standpipe goes in.

Is there a better way to connect this other than soldering that doesn't result in having to cut the slab?

 

[Sylvan]

Get a wire brush attached to a drill and CLEAN the lead sparkling trying to remove old solder.

Clean the copper standpipe and get 60- 40 bar solder for extra strength

What you have is a cup joint, and properly soldered, they last decades

WEAR Goggles. If you go on Google, they may have "lead wiping," like adding a brass ferrule to a lead bend