Installing a Replacement Vinyl window with brick mold

Good day,

I am trying to plan the replacement of an old window in my porch. The exterior of the house is aluminum siding. The existing window is the very old wooden, single pane vertical sliding type. There is a "storm" window covering the window on the exterior - basically a second window in an aluminum frame screwed over the existing window sorta sealing it from the elements! The aluminum siding doesn't come right up to the window, as there is a bit of a frame bordering the window on which this "storm" window is screwed to. I am wondering if I simply remove the storm window and existing wooden window and just fit the new window in the opening, screw it thru the window frame and into the surrounding studs, then just calk around the brick mold of the new window and the aluminum border?

I am worried about leaking!

Thanks, and will try to get some pics if my description isn't sufficient!

- Joe