Don't be shy with the BPEO, it is one of the few EO's that is more effective in higher quantities.
I have had success using it at 20 drops in 2 eggs. (though I use it at the moment at 24dps per 8 eggs (that's roughly 1kg base mix)).
For instance, the nutrabaits site advises 24 drops per 500gm basemix for a long term bait. That works out at 2ml per kilo of base mix!
Here are two suppliers I have used, both good prices. Beware VAT though. Even so, still works out cheaper than nutrabaits:
https://www.cotsherb.co.uk/oils-flowers-and-more/oils/cat_25.html
http://www.oils4life.co.uk/prodcat.asp?CatID=3&Essential Oils
Hi Nu Val is very attractive, but also very filling. Use very little as loosefeed while fishing. Also, make sure it's FRESH. Store the base mix in an airtight bucket and don't expose it to damp.
Hope that helps.
Oh and one more thing, if it were me, I'd be looking to add a touch of robin red for long-range attraction, and a sweetener to level off any bitterness from the proteins...