There are a number of things that complicate this scenario. Pre-1985 asset, family home converted to investment, inheritance, any depreciation claimed by you or whoever you inherited from all make this less than 100% straightforward to determine your CG. I’d seek an opinion from an accountant.
But then if you hold an investment asset for longer than 1 year, you should be entitled to a discount on your Capital Gains of 50% for tax purposes (at least with current legislation- Labor have indicated that they may change this if they win the next election). At first glance, this halves your CGT liability, but as mentioned above, your circumstances are complicated.
If I intend to sell my asset, I’ll take into account the implied CGT liability when assessing net worth. If I intend to hold my asset, I won’t.