Makaira 50SEa help needed

[mak1]

Hi
I have 600m of Jerry brown hollow on my reel already. I would like to have a 75m topshot of 1.2mm mono.
  I have a spool of 100lb Shimano hollow ace.
I would like to use to fill the rest of the reel, with room for a 75m 1.2mm mono top shot How many M of hollow ace could I get on to fill the reel

[boon]

What diameter is the JB on it already?

[mak1]

I don't know as it was spooled up by a shop I got it from all I know is 100# JB

[MarkT]

Well, it'll take what it takes... put 75m of the mono on then fill it with the hollow ace, attaching both with tape rather than spliced.  When the spool is full of the hollow ace mark the line then take it off. Take off the mono too. Splice in the hollow ace and wind on tight until you get to your mark then load on your mono.