Wow, that is a very nice looking Strat..! It reminds me of something, I can't quite place what..
It is hard to tell in the photo, but it looks like it was possibly stripped or refinished at some point, did it look like this when you originally owned it?
So many forces conspired in the 1970s to make Fender guitars "heavy"... I've heard that in 1975 CBS issued an ECO to stop "doubly kilning" the wood, so a lot of heavy "green" wood was going into guitars.
I've also heard that they were buying Ash from wherever they could find it.
I recently watched a Fender Custom Shop video series on their "tone woods", were they said they would use Alder for a heavier instrument in general.. (the Sean Spicer meets Louis C.K. guy also kinda disputes the northern/swamp ash distinction!)
Also in the 1970s guitarists were being told that "mass= SUSTAIN" and SUSTAIN was the holy grail of guitar "tone" in the 1970s.. Gibson was producing some real boat anchors and the kids were putting brass nuts and brass saddles on their "embarrassingly light" guitars..