If you find a well built 900 gallon acrylic tank new for $4500 then order me 10. I’d take a look if it’s only 45 minutes away. Most of that dirt will wipe off. What you want to look for is bubbles/white patches in the seams and cracks. The pump looks similar to a hammerhead/barracuda pump. Solid pumps. The rust id be hesitant on as they seize if not in use for a while. The sump looks pretty basic but will do the job.