What filler to use

[steplift20]

I went down to check on my baby(1978 steplift) cause a had to modify my bow rail and noticed that the bases are all falling apart , my question is this when I removed the bases the new base holes don't line up so I have to fill them and drill them, what should I use? I was thinking marinetex but what would you guys use? Am I right? Thanks all and hope you had a very merry Christmas and a happy and safe new year