Pension Top-up Dilemma

[Cardano]

I am due to receive my state pension in October 2028 so yesterday went to the Gov.UK site and checked my NI qualifying contributions and forcasted pension amount. The information provided shows that I have 30 qualifying years and can pay voluntary contributions for a further 4 years (so 34 years in total) at a total cost of £3,244.80. The pension forcast figures are as follows; with 30 years contributions pension of £10,528.07 per year; with 34 years contributions pension of £11,541.90 per year, I must point out that the forecast figure is in reality the amount that would be received based on todays pension rates. Based on the fact that the UK state pension has over the last 20 years increased on average 4% per year and one assumes this will continue my dilemma is do I do the 4 years top-up or do I stick with the £10,528.07 pension and use the £3244.80 to invest in a stock holding paying (today) a 8% dividend assuming that dividend will grow by 2% per year and the stock value will grow 2.25% per year.
I'm sure others have looked at this scenario and would be interested to hear your thoughts.