I am not familiar with Canadian Ins. laws and rules, but you might want to ask the insurance company what they based maximum collision payout value on.
Some policies state "Replacement Value" but have a hidden ceiling that is based on nonsensical values. Other companies will allow you to set the "Stated Value" and set the premiums accordingly. After an accident is usually to late to find out these little details.
Good luck on your 1st question, I would ask them WHY they need a 40 y.o. price.
For reference, the 1973 Hunter Compact-II was $2,495 USD, meaning the a Trillium
would have been somewhat higher than that number.