trader54321
is there a mfg date on the ballast? If it is 8 yrs old you shouldn't bother. Even new they tend to look pretty nasty and a lot of dated ones are still new years after manufacturing and sold at discounts. if it is 5 yrs old used for 3 yrs, don't bother. if its 1 or 2 yrs of use on it, use it. of course this is assuming your old magnetic ballast is going to wear the bulb down within the time frame of 400 hours of use.
how are the ufos? 90w how many LEDs? if the LED are 1-3w or greater per LED they are decent LED lights but LED is still no match with out breaking the bank.