Eight years should be more than enough! The average is two to four, and that's for a highly competitive, nationally ranked program. If you get any more than that 8 years under your belt you may in fact miss the window to persuade a school you need the MBA! Or they may suggest your professional skills are so advanced you're now a better fit for an executive MBA.
At eight years out, your GPA will not have much relevance. But your test scores might. Are they within the ballpark of the Business School you have targeted? If not, you don't mention if you have pursued test prep or private tutoring to try and retake the test and get your scores up. Low scores can be problematic. Try and improve your scores - but again only if they fall below the average of admitted students at this regional school. Happily, your recommendations and work experience will carry the most weight. So you should start working on shoring up standout recs. That said, you don't indicate what profession you are in, and whether you can count on great recommendations. You may be able to win admission to this regional school with low grades and so-so scores. But if you also submit ho hum recs, this could possibly doom your application.
My advice is you speak to the admissions officers at this regional school and see if you are a fit, and what they are looking for. If your scores and grades make them hesitant, consider taking a MBA class or two part time at a local university or in a respected online program and getting straight A's. You might then present this as evidence of your ability to perform well academically. Again, before embarking on this, I would inquire about whether this would be helpful.
Your reasons for wanting the MBA are sound, and should be music to any school's ears. If you do your homework, you should be able to find the one that fits!