FRPP 3:73's. HELP

Well i'm def getting rid of my stock 2:73's in my car now. I have a local mechanic that helps out at our shop and he'll help my put my gears in on my car on our hoist for free. So i figure why not change them. He helped out on my 5 lug conversion for free. Thank god for him ha. But what all do i need to do the swap. I see 50resto has some kit that they are asking out of there ass, but it seems like over kill. I know you need 3:73's gears, rear end oil, the correct speedo tooth gear, and since my cars a 91 i need a tail shaft gear to because they dont make a correct speedo tooth gear to get the mph right. What else is there to it? And how much exactly is the gain. Right now all i got is burn through first and cherp 2nd. Will i be able to burn 2nd finally? ha THanks for any help

Well yeah and the friction modifyer. I've already done my M-2300-K brake kit swap. I already drain the rear end and put the new axles in and all that but i wasn't smart enough to do the gears at the same time. But yes im def doing the tail shaft gear cause i've been told it wont read correctly and thats a must for me. Thats why i was almost thinking 3:55's? Because i wouldn't have to do any of that ****.

Well its not very hard to change the tail shaft gear though, and its very inexpensive also.