You would likely be best off by optimizing your Holley Tune-Up rather than attempt to add a secondary metering block. If you get the Tune-Up correct, it should work fine. Lots of parts are available to custom tune a Holley.
Yes, you could experiment with just adding the metering-block and longer-bowl-screws, plus a plug for the Power-Valve opening, but I believe it's not as simple as it may seem.
Certainly, if trying to fully convert to a 4150, though it's possible to do, there is more to the conversion than it's worth.
To do that, you would need to drill holes in the main-body and modify it quite a bit to put a secondary accelerator pump squirter, bowl w/ pump, secondary-shaft FOR accelerator-pump cam, pump-lever, etc, etc, plus secondary mechanical-linkage.... and after all that, it may not work right.
So, it is really not a worthwhile way to go about it.
Better to sell the 4160 and buy a 4150; Or, go to Holley.Com and/or buy a good Holley book and learn more about Tune-Up and upgrade parts selection.
Or, take it to a Carb shop that specializes in custom-tuning.
Here is a Link to Holley.Com:
Holley Tech and Tech Library Topics