As the builder/owner/pilot of a Corvair powered airplane I believe Mr. Panzera's estimate on "all up" FWF weight to be spot on. I had it estimated at 255lbs as I stated in the series I wrote on another site a few years ago:Pat Panzera, publisher of "Contact" magazine recently did something similar with a Corvair engine. I don't remember the details but IIRC it weighed 256 lbs. I should find that again for future reference.
SonexBuilders.net View topic - Corvair Engines - The Justification Series
My engine weighed in at 218 lbs but once you add all the other pieces that are part of the total weight forward of the firewall then the true "installed weight" can be known.
My complaint (if I had one - and I do) is claiming that an engine is below the certain manufacturer's required FWF limit and then sell a product that those with the ability to count parts, see the added pieces that are not weighed, and add weight numbers will know they are in violation of their own FWF limit. There are a number of engine suppliers that always "massage" the weight numbers in order to sell their engines or their airframes. I came into aviation believing that because of the risks involved in powered flight that most people would be straight up and honest in order to prevent people from getting injured of killed. Yes, years ago I was quite naïve and now I find it amazing that the plain truth is sometimes so hard to come by.
Sorry about the rant but engine weights have been a thorn in the side of experimental aviation for some time ...