This is where some pictures really come in handy. I really don't want to insult mine, or you intelligence, but I'm assuming you've removed the flex drive plate, the hydraulic pump drive shaft hooks to, on the front of the crankshaft pulley. While I have not had to remove the pulley on my 480C, I have a on the old 310B with gas engine, and there was more than ample room to get the pulley out.
I looked in my service manual, which happens to be laying right beside me, in the photo's such as they are, it shows removing the pulley while in the machine. On the other hand, it appears the whole front end is wide open, and we both know that's not right.
Other than removing the motor mount bolts, and transmission mount bolts, then raising the front of the engine enough to clear the front end casting, I don't see how you can do it any other way.
As for fixing the groove, from the crank seal, there are aftermarket kits that use a Speedi-Sleeve to fix that. This one will run you $56, the seal to match is $13. Although at this vendor, they appear to be out of stock.
https://www.epsstore.com/index.php/engine-exhaust/crankshaft/a155893.html It shouldn't be too hard to find another vendor though, that does have them in stock.