Council leaders have unveiled a new rescue package for the project months after it was turned down for funding by the Heritage Lottery Fund earlier this year.
Although the cost of a proposed extension and refurbishment has been brought down from Â£56.7m to Â£49m, Renfrewshire Council’s proposed contribution will go up from Â£15m to Â£26m.
The HLF is to be asked to stump up Â£10m rather than Â£15 million, with the council hoping that the Scottish and UK governments will provide Â£4m between them.
Renfrewshire Council leader Mark Macmillan said: “Although the museum is not due to be fully open until 2022, we plan to schedule the work in a way which will allow UK City of Culture activity to take place in the building during 2021, should we win the title. The final fit-out would take place the following year.
“While a revised architectural solution has reduced the project cost, we’ve been able to retain ambitious plans for an excellent visitor experience which delivers the original aims and vision of the project.
“And it is important to remember the planned museum would be very much a legacy project of Paisley 2021 - which should still bring large numbers of visitors to the town long after any UK City of Culture year was over.”
The council, which has scaled back the amount of building work involved in the project, expects visitor numbers to treble to around 125,000 a year.
However 30-year projections have been scaled back from Â£89m to Â£75 million in terms of the impact on the local economy, while it is now expected to create 160 jobs rather than 238.
The council leader added: “We’ve already made huge steps forward in recent years with our ambitious plans to use Paisley’s unique heritage assets to drive a transformation of Renfrewshire’s future.
“The museum proposals are the signature project of that and will create a lasting legacy for the town and wider area. That will include major tourist footfall to the High Street, and a multi-million-pound boost to the local economy, supporting new jobs and opportunities for local people.
“The project will also retell the inspirational stories of Paisley’s heritage and pattern by involving local people, provide an outstanding learning resource, and help change perceptions of the town at home and abroad.
“But transformation of that scale and ambition cannot be achieved without major investment and there is no option but for to the council to find its share of that.
“Major projects of this scale are rarely funded on the first ask, but the application process saw us receive some positive feedback about the ambition and viability of the project from funders. We also learned what we need to do to have a better chance of being funded next time – and that was to have a greater proportion of the project cost in place.
“The near-Â£7m reduction in cost and increased contribution from council resources will bridge that gap, while we now have a more robust fundraising strategy in place to bring in the rest of the investment needed from government and other sources.”