Replacing stock fuel pump with new mechanical fuel pump

I'm replacing the stock mechanical fuel pump with a new one, which is supposed to work with my engine. When comparing the new and old pumps, the lever/rocker arm on the new one protrudes about 2mm less than the old pump. It's also a different shape. It looks like this is the case for all aftermarket mechanical pumps I can find.
I intend to go electric at some point, but not until I buy a new carburetor. Will this 2mm difference stop things from functioning? Would a longer push rod help? Should I shave 2mm off the fuel pump spacer? The new and old spacers are exactly the same diameter btw.

Any help is appreciated, as always.

I can't figure how to post a photo, but here' a link to the two pumps side by side:
http://img.photobucket.com/albums/v4...psmicrgdiv.jpg

O.k A question first - did the original fuel pump come with a spacer? If it did then there's a good chance the new fuel pump will only require a gasket. 2 mm will make very little difference.

...and as for posting pics direct, I've struggled with this until I finally got it. When replying hit 'go advanced' then it will open up extra options. One of them below the dialog box (in the additional options) is 'manage attachments'. Hit that, click +add files, click either the 'select' first to pull an image straight from your pc or 'website' at the top of the pop up box and add the URL in the next pop up box. Not over yet. Now the image thumbnail will appear in the bottom of the image file album. Bottom right of that box is 'selected attachments' with 'insert inline' next to it.
Click on that - aaaand your image appears a few seconds later in your post. Clear as mud! :lmao:

Mine on the first gen had about a 1/4" thick fiber block.
So yes to the 4G63 with the large cam plugs

The original pump came with a spacer, which is identical to the new spacer. The spacer is 5mm thick. Removing that will make the new pump's rocker arm protrude 3mm further than the old pump with spacer.