I'm sorry to hear about your dad.
I just sold a similar 74 Spider for more than $5k, but stock with a little rust.
Put it on eBay and you should get $5k easy. If you bring it up to WA and restore the interior it's worth more like $10k, but as a sort of track car the market is limited.
Good luck, I'm a licensed dealer and long time Alfisti and happy to give a little free advice as you're in a tough spot. Just PM me.
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Ian Lomax - Current: 1973 Berlina, 1987 Milano Platinum "racecar"
Past: 71, 74 Spiders, 2x 74 Berlina, 74 GTV, 76 Alfetta GT, 88 Milano 3.0, 164LS