Basically nobody can tell you the strength of the frame you own. At the time it was made it did and still is supporting the 30-30 round that was chambered with the frame. What I do is closely inspect any Topper frame after doing some shooting with it. I look for any type of hairline crack developing, or anything else that looks abnormal. That is all we can do.
If you think you have any problem developing discontinue use and look around for another frame, preferably an SB2 to mate the barrel with. I have three Toppers with SB2 frames that are working out well.
I'm still trying to figure out if the SB2 frames made up to 1999 are any more fit to have a low pressure rifle barrels on them than an SB1 is. With these types of interchanges of barrels and frames as they say,"you spends your money and you takes your chances."
I know this didn't answer your question, but I don't think the answer is out there. Let us know what you do with the Max if you get one.